b2 module 3 test 2

MODULE 03 PRACTICE MCQ PART 02

http://www.aircrafttechtrng.com

An # represents the correct answer

322. The sum of the instantaneous E.M.F.'s in a three phase system is

a) equal to the line voltage

b) three times the phase voltage

# c) zero

323. A capacitor is a barrier to

a) both

b) A.C

# c) D.C

324. One revolution of a three phase generator will produce

a) 3 cycles

b) 2 cycles

# c) 1 cycle

325. If the North pole of a magnet is brought nearer to the North pole of another magnet

a) attraction between them will be increased

# b) repulsion between them will be increased

c) repulsion between them will be reduced



326. A 200 volt motor is taking 10 amperes armature current, the armature resistance is 0.1

ohm. The B.EMF under these conditions will be

a) 201 volts

# b) 199 volts

c) 1 volt

327. What is the effect of inserting an iron core into a current carrying coil?

# a) The flux density of the original magnetic field produced by the coil is increased

b) The flux density of the original magnetic field remains constant

c) The core tends to move from a stronger to a weaker part of the field

328. What is the total capacitance of a parallel circuit containing three capacitors with

capacitance of 0.25microfarad, 0.03microfarad, and 0.12microfarad, respectively?

a) 0.04 F

b) 0.04 pF

# c) 0.4 F

329. At resonant frequency the phase difference between the voltage and current of an AC

supply feeding an inductive and capacitive network is

# a) 0 degrees

b) 180 degrees

c) 90 degrees



330. The frequency of a power wave in an AC resistance circuit is

a) the same as the frequency for voltage and current

b) half the frequency for voltage and current

# c) twice the frequency for voltage and current

331. The reading on the ammeter in the circuit shown is

a) 3A

# b) 6A

c) 12A

332. The 'A' phase of a three phase power system is colour coded

a) blue

b) yellow

# c) red

333. The total resistance of the circuit shown is

a) 12 Ohms

# b) 3 Ohms

c) 7.5 Ohms



334. What is a method used for restoring generator field residual magnetism?

# a) Flash the fields

b) Reseat the brushes

c) Energize the armature

335. A 1F capacitor is equivalent to

# a) 0.000,001 Farads

b) 1,000,000 Farads

c) 0.001 Farads

336. The opposition offered by a coil to the flow of alternating current is called (disregard

resistance)

a) impedance

b) reluctance

# c) inductive reactance

337. A high surge of current is required when a DC electric motor is first started. As the speed

of the motor increase

a) the applied emf increases proportionally

b) the counter emf decreases proportionally

# c) the counter emf builds up and opposes the applied emf, thus reducing the current flow

through the armature



338. The tolerance of the AC generator frequency is

a) 40 Hz

# b) 10 Hz

c) 20 Hz

339. The various parts of an aircraft airframe are maintained at the same potential by

a) the supply bus-bars

b) static discharge wicks

# c) bonding

340. When two capacitors are connected in series

a) the charge stored on each is directly proportional to its capacitance

# b) the charge stored on each is the same

c) the charge stored on each is inversely proportional to the voltage across it

341. Aircraft generators are cooled by

a) oil cooling radiators around the main body

b) fuel cooling radiators

# c) ram air



342. The voltage of an AC generator

a) rises to max in one direction, falls to zero and rises in the same direction

# b) rises to max in one direction then falls to zero then rises to max in the opposite

direction

c) rises to max in one direction and remains

343. The charge on a capacitor is expressed as

a) the ratio Q/V

b) the product Q x V

# c) the product C x V

344. A shunt is used with

# a) an ammeter

b) an ohmmeter

c) a voltmeter

345. The resistance of the current return path through the aircraft is always considered

negligible, provided the

a) generator is properly grounded

b) voltage drop across the circuit is checked

# c) structure is adequately bonded



346. An ammeter is connected into a circuit in

a) parallel

b) shunt

# c) series

347. When handling a high voltage capacitor in an electrical circuit, be sure it

a) has a full charge before removing it from the circuit

# b) is fully discharged before removing it from the circuit

c) has at least a residual charge before removing it from the circuit

348. When a circuit with a series inductance and capacitance is at resonant frequency

a) the current in the circuit decreases

# b) the impedance of the circuit is such that the voltage is in phase with the current

c) the impedance of the circuit is such that the voltage leads the current by exactly 90

degrees

349. in an AC circuit, the effective voltage is

a) equal to the maximum instantaneous voltage

b) greater than the maximum instantaneous voltage

# c) less than the maximum instantaneous voltage



350. On a combined DC starter - generator system

# a) the voltage regulator is connected to the shunt field after the start cycle is completed

b) the series coil is open circuit during the engine start sequence

c) the voltage regulator controls the start sequence during engine starting

351. A pure capacitor, inductor and resistor are connected in series and the voltage drops

across each are 10V and the total current flowing in the circuit is 1A. How much true power

is the circuit consuming?

a) 30VA

b) 30W

# c) 10W

352. If a capacitor 1F and an inductor 10mH are connected in parallel what is their

approximate resonant frequency?

a) 62Hz

b) 3.2MHz

# c) 1.6kHz

353. Which wave form is stepped positive and negative with unequal length sides?

# a) Trapezoidal wave

b) Rectangular wave

c) Saw tooth wave



354. The value of an AC sine wave that will give an equivalent heating effect in a DC resistor

is the

a) average value

# b) RMS value

c) peak value

355. Where is the magnetic dip least?

a) Poles

# b) Equator

c) Isoclinals

356. The dielectric constant of a capacitor is a measurement of

# a) the electrostatic energy storing capacity of the capacitor dielectric

b) the electrical resistance of the capacitor dielectric

c) the electrical repulsion of electrons within the dielectric material

357. To reverse the direction of rotation on a DC shunt motor, you must change the direction

of the current through

# a) the field windings or the armature windings

b) the armature windings only

c) the field windings and the armature windings



358. If the field current to a shunt wound DC motor is decreased when operating at a constant

load, the motor speed will

a) reduce

# b) increase

c) not change

359. An electric current is

a) a surplus of free electron

b) an excitement of electrons in a metal

# c) an ordered flow of electrons

360. An atom contains

a) molecules

b) hydrogen

# c) electrons

361. What causes a transformer to be noisy?

a) High coil resistance

# b) An air gap in the core

c) High core losses



362. Carbon has a

# a) negative temperature coefficient

b) positive temperature coefficient

c) temperature coefficient of zero

363. The peak factor for a sine wave is

a) 0.707

# b) 1.414

c) 1.11

364. If a motor is spinning at 50 cycles per second, how long is 1 cycle?

# a) 0.02 seconds

b) 50 seconds

c) 0.83 seconds

365. An integrated step input at unequal time base produces

a) a square wave

b) a sine wave

# c) a saw tooth wave



366. A capacitor in series and inductor in parallel make what kind of filter?

a) Band pass

# b) High pass

c) Low pass

367. If a load in series has a current passing through it, the magnetic field can be worked out

by using

# a) the corkscrew rule

b) left hand rule

c) right hand rule

368. If the current flowing into a junction is 5A, 3A, 4A in and 10A out. What is the 5th wire

carrying?

a) 2A in

# b) 2A out

c) 5A out

369. If an insulated conductor is placed near to a negatively charged rod, the nearest end of

the conductor becomes

a) negatively charged

# b) positively charged

c) No change will occur



370. If 2 resistors, one red, yellow, black, gold and the other violet, blue, black, silver were

replaced by a single resistor. Ignoring tolerance, what would the color coding be?

# a) Brown, black, brown

b) Brown, black, black

c) Black, brown, black

371. Germanium and silicon have how many electrons in their outer shell

# a) 4

b) 2

c) 6

372. If a free electron is given to another atom, that atom is a

a) positive ion

# b) negative ion

c) valency atom

373. If a nicad battery is not to be used immediately it should be stored

a) fully charged

# b) fully dissipated

c) dry



374. A light / heat sensitive cell is a

# a) transducer

b) diode

c) transistor

375. In a mercury cell the steel casing is

# a) the positive terminal

b) the negative terminal

c) neither

376. To improve the life of a dry cell you would

# a) use more zinc

b) use more electrolyte paste

c) us a a pure carbon positive rod

377. What is the voltage at A?

# a) 26V

b) 28V

c) 2V



378. The unit for power is equal to

a) N/m

# b) Joules per second

c) Volts/Amps

379. The source voltage in the circuit below is

a) 50V

# b) 200V

c) 150V

380. The 5th colored band on a resistor represents the

a) tolerance

b) multiplier

# c) reliability or temperature coefficient

381. Three 12 microfarad capacitors in parallel. The overall circuit capacitance is

a) 4 microfarads

b) 1 microfarads

# c) 36 microfarads



382. Flux density will

a) increase linearly with coercive force

# b) increase linearly with magnetic flux

c) decrease linearly with magnetic flux

383. A transformer with a 5:1 ratio has a 24V output. What is the input

a) 120 V DC

b) 4.8 V AC

# c) 120 V AC

384. The mark-to-space ratio of the following waveform is

a) A to B

B to C

# b) A to D

D to E

c) D to E

D to C



385. A generator supplies 25 A, 4 V and 50 W. What is the apparent power and the power

factor?

a) 100 VA and 2

b) 400 VA and 0.5

# c) 100 VA and 0.5

386. In a power circuit, the purpose of an inductor is

# a) to dampen power surges

b) to dampen current surges

c) to dampen voltage surges

387. When a number of ferrite pieces are grouped together, they

a) are semi-permanent magnets when DC is passed through them

# b) can be used to store binary code

c) electromagnets

388. Ampere turns is calculated by the number of turns

# a) multiplied by current

b) divided by current

c) multiplied by magnetic flux



389. A conventional aircraft generator will be

a) series wound

b) delta wound

# c) star wound

390. Storage of magnets should be

a) in pairs end to end

b) in a non magnetic pox

# c) in pairs with keeper plates

391. A circuit has 1 megohm and 8 microfarads. What is the time constant?

a) 1 second

# b) 8 seconds

c) 40 seconds

392. Current in an inductive circuit will

a) lead voltage

# b) lag voltage

c) be at unity



393. Power factor of a generator is

a) sin

# b) cos

c) tan

394. In a an AC motor, the rotation of the MNA

a) is the same as the rotation of the armature

# b) is opposite to the rotation of the armature

c) is slightly less speed than the rotation of the armature

395. in a wave wound generator with 4 poles, what would be the minimum number of

brushes?

a) 4

# b) 2

c) 8

396. A capacitor rating is

# a) the maximum continuous voltage it can take

b) the voltage it will rupture at

c) the voltage it will charge to



397. in conventional flow, the left hand rule applies to

a) generators

# b) motors

c) batteries

398. Copper losses in a transformer are caused by

a) circulating currents through the transformer

# b) the resistance in the windings

c) wasting of the copper wires due to friction

399. in AC generators, 0.637 is

a) RMS

# b) average value

c) form factor

400. In a 3 phase generator, what angle are the phases to each other?

a) 180o

# b) 120o

c) 0o



401. In a 2 phase generator, what angle are the phases to each other?

# a) 90o

b) 180o

c) 0o

402. Delta wound line current is

a) equal to phase current

# b) root 3 x phase current

c) less than the phase current

403. The multiplier color coding on a capacitor is in

a) farads

b) microfarads

# c) picofarads

404. Form Factor for a sine wave AC output is

a) 0.707

b) 1.414

# c) 1.1



405. In a simple voltaic cell the collection of ions on the cathode causes

a) hydration

# b) sulphation

c) polarisation

406. The electrolyte in a nicad battery would rise if the battery was

a) discharging

# b) charging

c) remaining at constant voltage

407. When a conductor is cut by magnetic lines of force an EMF is induced. This is

a) Lenz's Law

# b) Faraday's Law

c) Kerchoof's Law

408. Two 2 volt 10AH cells are connected in series, the output voltage and the capacity would

be

a) 2 volt, 20 AH

# b) 4 volt 10 AH

c) 4 volt 20 AH



409. The electrolyte in a nicad battery is

a) cadmium hydroxide

b) nickel hydroxide

# c) potassium hydroxide

410. Referring to the drawing below, if the volts dropped across the 20 ohm resistor is 10

volts, the resistance of R1 is

# a) 20 ohms

b) 16 ohms

c) 2 ohms

411. The atomic number of an atom is determined by the number of

# a) protons

b) electrons

c) neutrons

412. In a Leclanche cell the plates are made of

a) mercury and lithium

b) nickel and cadmium

# c) zinc and carbon



413. in a simple voltaic cell, polarization reduces output voltage because of the

a) transfer of material between the anode and the cathode

# b) build up of hydrogen on the anode

c) build up of hydrogen on the cathode

414. When the temperature of the electrolyte in a battery increases, the SG

a) goes up

# b) goes down

c) remains the same

41 5. A 47 kilohm resistor has the following color code

# a) Yellow, Violet, Orange

b) Orange, Violet, Red

c) Red, Orange, Yellow

416. If the temperature of a pure metal is reduced to absolute zero, its resistance will be

a) infinity

# b) practically zero

c) unaffected



417. The bridge circuit shown will be balanced when the value of the unknown resistor R is

a) 18 ohms

b) 14 ohms

# c) 2 ohms

418. The current in the circuit below is

a) 5 A

b) 0.2 A

# c) 5 mA

419. In the previous question, the power developed across the 10 k ohm resistor is

# a) 250 mW

b) 250 W

c) 50 mW

420. What is represented by this diagram?

# a) Potentiometer

b) Rheostat

c) Thermister



421. In the following circuit, the input at P is 4 amps and at Q is 5 amps. What is the voltage

across the 6 ohm resistor?

# a) 54V

b) 1.5V

c) 6V

422. The unknown current in the network below is

a) 22A

# b) 3A

c) 47A

423. The Watt can be expressed as

# a) Joules per second

b) Joules x seconds

c) Seconds per Joule

424. A single phase circuit has an input voltage of 100V. The current is 10A and the circuit

has a power factor of 0.5. The true power is

a) 1000W

b) 50W

# c) 500W



425. Power in a DC circuit is found by

a) multiplying current by resistance

b) multiplying the voltage by itself and dividing by the current

# c) multiplying the resistance by the current squared

426. The total capacitance of the circuit shown is

# a) 4F

b) 36F

c) 3F

427. When a capacitor is charged from a DC supply, the voltage / time curve is

a) logarithmic

# b) exponential

c) linear

428. An electrolytic capacitor is used because it has a

a) large physical size for a large capacity

# b) small physical size for a large capacity

c) small physical size for low leakage current



429. An electrolytic capacitor would be used in circuits supplying

a) heavy loads

b) light loads

# c) heavy / light loads

430. The symbol for flux density is

a) H

# b) B

c) MMF

431. The hysteresis loop for a magnetic material is on a graph with

a) total flux against flux density

b) current against flux density

# c) flux density against magnetising force

432. To determine the direction of the magnetic field around a conductor you would use

# a) the corkscrew rule

b) Fleming's left hand rule

c) Fleming's right hand rule



433. A material with a narrow hysteresis loop

a) will have high retentivity

# b) will have low retentivity

c) cannot be magnetised

434. If a bar magnet is cut in half

a) the magnet is destroyed

# b) two bar magnets are formed

c) one bar magnet and one non-magnet is formed

435. The diagram shows a current carrying conductor in a magnetic field. The conductor will

move

a) upwards

# b) downwards

c) sideways

436. The electromagnetic force between two charged bodies is

a) proportional to the distance between them

b) inversely proportional to the distance between them

# c) inversely proportional to the square of the distance between them



437. Copper is a

a) paramagnetic materials

b) ferromagnetic material

# c) diamagnetic material

438. Switching on or off the current in one coil produces an emf in another coil adjacent to it.

The two coils are said to have

a) self inductance

# b) mutual inductance

c) auto inductance

439. the time constant in an inductive circuit is the time required for the current to reach

# a) 63.2% of maximum value

b) 63.7% of maximum value

c) 70.7% of maximum value



440. Self induced emf in a coil supplied with a current varying at a uniform rate can be found

by

a) - N dI

dt

b) - L d

dt

# c) - L dI

dt

441. The MMF of a coil fed with 2 amps and having 10 turns is

a) 5 ampere turns

# b) 20 ampere turns

c) 20 amperes / turn

442. An AC inductive circuit has an inductance 0f 10 mH and a frequency input of 1000Hz.

The opposition to current flow is approximately

a) 63,000 ohms

b) 630 ohms

# c) 63 ohms



443. A sine wave of RMS value 7.07 volts has a peak to peak value of

a) 10.0 volts

b) 0.707 volts

# c) 20.0 volts

444. The true power in an AC circuit is given by

a) voltmeter reading x PF

b) volts x amps

# c) volts x amps x PF

445. The average value of 100 volts peak AC is

a) 70.7 volts

b) 141.4 volts

# c) 63.7 volts

446. The RMS value of 200 volts peak to peak is

a) 141.4 volts

# b) 70.7 volts

c) 127.4 volts



447. The impedance of a series tuned circuit at resonance is

a) zero

b) maximum

# c) minimum

448. The copper loss on a single phase transformer is 25 Watts on full load. What will it be on

half load?

a) 5 Watts

b) 12.5 Watts

# c) 6.25 Watts

449. Rotating coil B through 90o will

a) increase the EMF induced into B

# b) decrease the EMF induced into B

c) increase the EMF induced into A

450. A transformer is designed to operate at 60 Hz. It is connected across a 50 Hz supply.

The primary windings would

# a) draw more current

b) draw less current

c) draw the same current



451. A current transformer, when disconnected from a circuit must be

a) left open circuit

# b) short circuited

c) have a resistor connected across the terminals

452. What is the reflected impedance in the primary?

a) 20 ohms

# b) 500 ohms

c) 50 ohms

453. A transformer rated at a frequency of 200 Hz

a) may be used at any other frequency

# b) may only be used at the rated frequency or above

c) may only be used at the rated frequency or below

454. The dots are called, and indicate

a) quadrature dots, points are 90o out of phase

# b) phasing dots, point that have the same polarity at the same moment in time

c) phasing dots, point that have the opposite polarity at the same moment in time



455. The power factor of an AC circuit is the

a) sine of the phase angle

# b) cosine of the phase angle

c) tangent of the phase angle

456. The Form Factor of an AC waveform can be found by

# a) RMS value divided by the average value

b) average value divided by the RMS value

c) average value times the RMS value

457. A differentiator has a time constant which is

a) long

# b) short

c) equal to the input pulse

458. If the frequency is increased in an AC circuit of pure resistance, the effect is

a) increased resistance

b) decreased resistance

# c) nothing



459. A wire is rotated through a magnetic field. To give DC it must be connected to

# a) a commutator

b) slip rings

c) a rectifier

460. In an inductive resistive circuit, 1 amp flows from a supply of 100V dissipating 50 Watts

of power. The phase angle is

# a) 60o

b) 90o

c) 45o

461. A transformer is built with a material having a

# a) narrow hysteresis loop

b) wide hysteresis loop

c) high coercive force

462. An alternator delivers 500V RMS at 1 ampere. The power factor is 0.8. The true power

is

a) 100VA

# b) 400W

c) 500W



463. in a circuit which possesses mutual inductance, current is increased to the primary

# a) the induced EMF in the secondary produces a current in the secondary circuit which

opposes the increase in flux due to the increase of current in the primary

b) the induced EMF in the secondary produces a current in the secondary circuit which

assists the increase in flux due to the increase of current in the primary

c) the induced EMF in the secondary produces a current in the secondary circuit whose

flux has no effect on the flux in the primary

464. A component that produces an output voltage due to incident light is called a

a) liquid crystal

b) light emitting diode

# c) solar cell

465. If the supply to a DC shunt motor was reversed

a) it would rotate in the opposite direction

b) it would fail to run

# c) it would rotate in the same direction

466. Slip on a synchronous motor on start is

a) 0%

b) 50%

# c) 100%



467. A shaded pole motor has shaded poles to

a) increase efficiency

# b) create a rotating field

c) reduce interference

468. A series motor draws a high current on start, and then the current reduces. This is due

to

a) the resistance of the field and the armature in series

# b) the back EMF

c) the resistance of the field and armature in parallel

469. on a brushless AC generator, the main rotating field is fed with

a) AC

# b) DC via diodes on the rotor

c) AC from the rotating field exciter

470. Single phase components in a three phase system may be connected between

a) phase A and B only

b) phase and neutral only

# c) any phase and neutral OR between any two phases



471. Interpoles in a DC generator are connected

a) in parallel with the armature

# b) in series with the armature

c) in series with the field

472. in a DC generator, the effect of armature reaction may be reduced by moving the brush

gear

a) from MNA to GNA

# b) in the direction of armature rotation towards the MNA

c) against the direction of armature rotation towards the MNA

473. The windings embedded in the pole faces of a DC generator are

a) interpoles

b) commutating coils

# c) compensating windings

474. A 6 pole wave-wound generator has

# a) 2 brushes

b) 6 brushes

c) 3 brushes



475. In a 2 phase induction motor the control winding is fed with

a) variable phase AC supply

b) fixed AC supply

# c) variable amplitude supply only

476. A 3 phase induction motor can be reversed by

a) isolating one phase

b) reversing the rotor connections

# c) changing over any two phases

477. The speed of an AC motor can be affected by the

a) field current

# b) pairs of poles

c) armature current

478. A generator rated at 30 KVA and power factor 0.8 has a maximum continuous power

output of

a) 30 kW

# b) 24 kW

c) 37.5 kW



479. An AC motor which rotates at the same speed as the supply frequency is called

a) a universal motor

b) an induction motor

# c) a synchronous motor

480. In the circuit shown, impedance will be

a) 9 ohms

# b) 5 ohms

c) 7 ohms

481. In the circuit shown, if the frequency is increased from zero to resonant frequency, the

circuit current would

# a) increase

b) decrease

c) stay the same

482. The true power developed in this circuit is

# a) 12W

b) 50W

c) 20W



484. An example of a paramagnetic material is

# a) iron

b) silver

c) glass

485. in a balanced Wheatstone bridge, across the centre of the bridge there is

# a) no current flow

b) no voltage present at either end

c) current and voltage at maximum

486. A 24V battery has an internal resistance of 1 ohm. When connected to a load, 12 amps

flows. The value of the load is

a) 12 ohms

# b) 1 ohm

c) 1/2 ohm

487. The property of a material to accept lines of flux is called

# a) permeability

b) reluctance

c) retentivity



488. Armature reaction in a DC generator causes

# a) MNA to move in the direction of rotation

b) MNA to move in the opposite direction of rotation

c) GNA to move in the direction of rotation

489. in a DC motor, B-EMF rises if the motor

# a) speed rises

b) speed falls

c) load rises

490. Vibration in a magnet causes

a) flux to increase

# b) flux to decrease

c) flux to stay the same

491. A high pass filter has

# a) high impedance to low frequency, low impedance to high frequency

b) high impedance to high frequency, low impedance to low frequency

c) high impedance to both high and low frequency



492. What sort of wave would be used in a CR oscillascope to control sweep?

# a) Sawtooth

b) Square

c) Sine wave

493. If there was a mainly inductive load on an AC generator, the voltage with respect to the

current would

# a) lead

b) lag

c) be in phase

494. on a brushless AC generator, the permanent magnet generator output is

a) DC

# b) AC

c) pulsed

495. The output from a rotating armature AC generator would be taken from

# a) the rotor

b) the stator

c) either the rotor or the stator



496. A frequency wild AC generator system has

a) variable voltage and frequency

# b) variable frequency only

c) variable voltage only

497. in a series LCR circuit at resonance, R = 100 ohms, L and C are each 10 ohms. The total

impedance is

# a) 100 ohms

b) 30 ohms

c) zero ohms

498. An AC generator has four poles. To produce a frequency of 400Hz it must achieve a

speed of

a) 6000 RPM

b) 8000 RPM

# c) 12000 RPM

499. If an AC sinewave has an RMS value of 5V its peak value is

a) 14.14 V

b) 6.37 V

# c) 7.07 V



500. The Daniel Cell electrodes are

# a) copper and zinc

b) carbon and zinc

c) zinc and manganese dioxide

501. An inductor of resistance 5 k ohms and inductance 2mH is connected to a DC circuit.

The time constant is

# a) 400 ns

b) 10 seconds

c) 40 ms

502. The unit of flux is the

# a) Weber

b) Ampere turns

c) Ampere turns / metre

503. The flux density of a magnetic field is 1.5T. The length of the conductor in the field is 2

m and the speed of the conductor is 10 m/s. The EMF induced is

a) 0.3 V

# b) 30 V

c) 7.5 V



504. A DC generator armature has 6 poles and is lap wound. The number of brushes

required are

# a) 6

b) 2

c) 3

505. Reactive sparking is reduced by

# a) interpoles

b) compensating windings

c) auxiliary windings

506. The back EMF in a DC motor is

a) equal to the applied EMF

# b) less than the applied EMF

c) greater than the applied EMF

507. The flux density of a magnetic field is 1.5T. The length of the conductor in the field is 2

m and the current flowing through the conductor is 5 amps. The force on the conductor is

# a) 15 Newtons

b) 0.6 Newtons

c) 3.75 Newtons



508. A DC shunt motor has 28 volts applied. The current taken from the armature of 2 ohms

resistance is 1 amp. The BEMF is

a) 30 V

b) 27 V

# c) 26 V

509. in a motor, armature reaction causes the MNA to move

a) in the direction of rotation

# b) against the direction of rotation

c) to the GNA

510. A circuit with good selectivity will have

a) a large bandwidth

# b) a narrow bandwidth

c) a low L/C ratio

511. Apparent power in an AC circuit is found by

# a) V x I

b) V x I x cos

c) V x I x sin



512. A 300 ohm resistor would have a colour code of

a) orange, orange, brown

b) orange, brown, black

# c) orange, black brown

513. in a synchronous motor, when the motor is running the slip is

a) 100%

b) 5%

# c) 0%

514. In a two-phase induction motor there are

a) 2 poles

b) 3 poles

# c) 4 poles

516. A transformer has 500 turns on the primary and 100 turns on the secondary. When

connected to a 100 V supply, the output is

a) 500 V

# b) 20 V

c) 25 V



517. in the previous question, the secondary is connected to a 10 ohm load. The primary

current is

a) 10 amps

# b) 0.4 amps

c) 2 amps

518. Magneto motive force can be found by

a) N/I

# b) I x N

c) Blv

519. Permeability of a material can be found by

# a) flux density / MMF

b) MMF x flux density

c) MMF / flux density

520. A filter with a small bandwidth has

# a) a high value of Q

b) a low value of Q

c) a Q of zero



521. A transformer has 1200 turns primary and 4800 turns secondary. What value of load

resistance would be required to give a reflected impedance of 1000 ohms

a) 1 kohm

b) 4 kohm

# c) 16 kohm

522. An autotransformer windings are

a) on separate formers

# b) connected

c) wired in parallel

523. What voltage can the neutral line carry in a star transformer?

a) Combined line voltages

# b) Zero voltage

c) Phase voltage

524. in a generator system, a stabilizing winding is used

a) in series with the field to prevent oscillations

# b) to prevent voltage overshoot

c) to control output current



525. When magnetizing a piece of material, magnetic strength will rise

a) linearly with coercive force

b) linearly with magnetic force

# c) non-linearly with magnetic force

526. The stator of a permanent magnet rotor AC generator

a) is wound in series with the field

b) is usually delta wound

# c) is usually star wound

527. In a resistive/inductive motor

# a) the resistor circuit must be disconnected after starting

b) is less efficient than a capacitor start motor

c) can only be used for light loads

528. When a conductor is cut by magnetic lines of force an EMF is induced. This is

a) Lenz's Law

# b) Faraday's Law

c) Kirchoff's Law



529. A 47K resistor has the following color code

# a) Yellow, Violet, Orange

b) Orange, Violet, Red

c) Red, Orange, Yellow

530. A material with a narrow hysterisis loop

a) has a high retentivity

# b) has a low retentivity

c) cannot be magnetised

531. The power output of a similar sized 3 phase compared to a single phase generator is

a) less

b) same

# c) more

532. What part of a DC motor would you find the poles?

a) brushes

# b) stator

c) rotor



533. in a high Q parallel resonant circuit, what happens to impedance if capacitance is

increased by a factor of 4?

# a) It reduces by 75%

b) It remains the same

c) It increases by factor of 4

534. In a thermocouple where is voltage measured?

a) At the hot junction

# b) At the cold junction

c) At both junctions

535. Mercury cells are covered with a metal cover

a) as a protective cover

# b) as a positive terminal

c) as a negative terminal

536. When switching off the supply, the back emf in a collapsing field in an inductor

a) never exceeds forward emf

# b) can be multiple times bigger than forward emf

c) is equal to forward emf



537. If the energy supplied to a circuit for 4hrs 15 mins at 800 j/sec what would be the energy

consumed?

# a) 3.4 KW Hrs

b) 3400 KW Hrs

c) 340 KW Hrs

538. A parallel circuit at resonance has its impedance at a

# a) maximum

b) minimum

c) zero

539. A parallel circuit with any number of 2 terminal connections

a) has the same current throughout

# b) the individual voltage drops is equal to the emf

c) the resistance is dependent on current

540. In this circuit, Rx is equal to

# a) R3 x R2 R4

b) R3 x R4 R2

c) R2 x R4 R3



541. A transformer to supply a 24V load with a 5:1 turn's ratio will have what primary

supply?

a) 120 VDC

b) 48 VAC

# c) 120 VAC

542. A material exposed to heat will

# a) be harder to magnetise

b) be easier to magnetise

c) have no effect on magnetism

543. A 20 Pico farad capacitor with a 1MW resistor takes how long to charge?

a) 20 milli seconds

# b) 0.1 second

c) 10 seconds

544. A transformer has 2000V, 500 turns on the primary and 50 turns on the secondary. What

would be the line voltage if the transformer were Delta/Star connected?

a) 200V

# b) 346V

c) 450V



545. The main advantage of a starter-generator over conventional units is

a) for the same power output there is a weight reduction and the starter drive remains

engaged

# b) for the same power output there is a weight reduction and the drive is constantly

engaged

c) it can produce a greater power output

546. The speed of a single phase induction motor is dependant on

a) the strength of the field

# b) the number of pairs of poles

c) the strength of the armature current

547. An A.C. shunt wound motor sometimes uses a volts dropping resistor. The resistor would

be

# a) in series with the supply

b) in series with the field

c) in series with the armature

548. The time to fully charge a 1 micro farad capacitor in series with a 100K ohm resistor is

# a) 100 ms

b) 10 ms

c)1 ms



549. A sine wave has a periodic time of 0.5 milliseconds, what is its frequency?

a) 200 Hz

# b) 2Khz

c) 20Khz

550. In a voltage equalizing circuit the generators are regulated so

a) the lower output is increased to that of the higher

b) the higher output is decreased to that of the lower

# c) the lower is increased and the higher is decreased until they are equal

551. The capacity of a battery is measured in

a) volts

b) cubic centimeters

# c) ampere-hours

552. Phase angle is

# a) the difference in degrees of rotation between 2 alternating voltages or currents or a

voltage and a current

b) the difference in degrees between the positive and negative parts of an ac sine wave

c) the cosine of the peak value of an ac voltage



553. A battery's internal resistance is determined by

# a) IR = OCV CCV

i

b) IR = OCV + CCV

i

c) IR = OCV - CCV

V

554. The impedance of an ac circuit is measured in

a) kilovolt-amperes

b) amperes

# c) ohms

555. The formula for impedance in a series circuit is

# a)

b)

c)

556. Motor slip is

# a) the percentage of difference in speeds between the stator and rotor fields

b) a shifting of the MNA of the motor

c) a symptom of a weak field



557. The principal characteristic of a synchronous motor is

# a) it rotates at a speed that is synchronised with the applied ac current

b) it must have a synchronised 3 phase supply to operate

c) it rotates at a speed that is synchronised with the applied dc current

558. There are more negative than positive plates in a lead acid battery because

# a) the positive plates are prone to warping if the chemical action is taking place only on

one side

b) it reduces the internal resistance of the cell

c) it is necessary for chemical action to take place

559. Commutator ripple can be reduced by

# a) the use of a ripple filter

b) increasing generator frequency

c) a resistor in series with the armature

561. What is the internal resistance of a Leclanche cell?

a) 6 ohms - 10 ohms

# b) 0.02 ohms - 4 ohms

c) 20 ohms - 30 ohms



562. In a DC motor the interpoles are part of the

# a) field

b) rotor assembly

c) stator assembly

563. The line voltage in a wye wound transformer is

a) root 3 / phase voltage

b) the same as phase voltage

# c) root 3 x phase voltage

564. The valence electron is

# a) the electron in outer shell of atom

b) the electron in inner shell of atom

c) a positive electron

565. An aircraft battery on charge from the aircraft generators causes

a) internal resistance of the battery to decrease in sympathy with the decreasing charging

current

# b)battery voltage to increases to nominal voltage and the charge current decreases

c) battery voltage to decrease to zero until it is fully charged



566. What happens to the current in a series resistive resonant circuit?

# a) It is maximum

b) It is minimum

c) It is zero

567. An atom with a deficiency in electrons has

a) high resistance

# b) low resistance

c) high impendence

568. What effect does hydrogen have in a battery cell?

# a) Polarization

b) Sulphation

c) Nothing

569. Eddy current losses in a transformer are

# a) current used in magnetising the core

b) current flow induced into the core

c) hysteresis losses



570. A 3-phase star-delta wound transformer gives

a) 90 phase shift

b) no phase shift

# c) 30 phase shift

571. In a parallel circuit containing resistors

# a) the voltage is the same in all parts of the circuit

b) the sum of the voltage drops equals applied voltage

c) resistance is determined by value of current flow

572. An induced current in a coil

# a) opposes the EMF producing it

b) aids the EMF producing it

c) does not affect the EMF producing it

573. Armature reaction is

a) reactive sparking

b) due to dirty or worn commutator

# c) the MMF opposing rotation



574. in a 4:1 step up transformer, what would give a reflected impedance of 1K ohm

a) 1 k ohm

b) 4k ohm

# c) 16k ohm

575. Lines of magnetic flux pass from

# a) N to S

b) E to W

c) S to N

576. A shunt motor

a) gives constant torque with variations in speed

# b) is constant speed

c) has high starting torque

577. The direction of current in a wire rotating in a magnetic field can be determined by

# a) Fleming's right hand rule

b) Fleming's left hand rule

c) cork screw rule



579. in a parallel LCR circuit, if the capacitance is increased by 4 times, what happens to the

impendence?

a) increases by 4 times

# b) decreases by 75%

c) remains the same

580. in a DC shunt motor, if the field resistance is increased what happens to the back EMF?

a) increases

# b) decreases

c) remains the same

581. Why is ferrite used in memory circuits?

# a) High remanence

b) Low permeability

c) High reluctance

582. What semi-conductor material is used in memory circuits?

# a) Ferrite

b) Permeomag

c) Iron



583. The discharge curve of a capacitor is

a) Linear

b) Logarithmic

# c) Exponential

584. to generate electricity with a fuel cell, you need a constant supply of

# a) Oxygen & Hydrogen

b) Kerosene & Heat

c) Nitrogen & Sunlight

585. Five different value resistors all have the same voltage dropped across them, how are

the resistors connected?

a) In Series

# b) In Parallel

c) In Series/Parallel

586. The input is 115V and is applied across the 300 turn portion. What is the output?

# a) 460V

b) 115V

c) 28V



587. A near perfect 4:1 step up transformer has it's primary connected to 120VAC, if the

secondary is connected to a load with 1600 ohms resistance what is the current in the primary

a) 1 amp

b) 0.3 amps

# c) 1.2 amps

588. Flux losses in a transformer can be prevented by

a) the use of primary shielding

# b) winding the primary on top of the secondary

c) laminating the core

589. A ni-cad battery found to be below normal capacity should

a) be removed and used for ground use only

# b) be re-charged with a freshening charge

c) have its electrolyte adjusted

590. In cold weather a battery must be kept

# a) fully charged

b) fully discharged

c) does not matter



591. A simple basic induction motor has

# a) poor starting torque, good running torque

b) good starting torque, poor running torque

c) poor starting torque, poor running torque

592. If the frequency to a capacitor increases, the current through it

# a) is zero

b) increases

c) decreases

593. In a 3-phase delta wound circuit, line current is

a) same as the phase current

b) in phase with the phase current

# c) the vectorial sum of all 3 phase currents

594. Conductance of a circuit is 2 milliMhos. What is its resistance?

a) 5 MegaOhms

# b) 500 Ohms

c) 5000 Ohms



595. To increase the voltage output of a generator you can

# a) increase speed

b) decrease speed

c) It is not speed dependant

596. How would you find the direction of the current flow in an armature located in a

magnetic field?

a) Maxwells corkscrew rule

# b) Flemings right hand rule

c) Fleming's left hand rule

597. If in a electrical circuit there is a difference between the capacitive reactance and the

inductive reactance, what would the power factor of the circuit be?

a) Unity

# b) Less than unity

c) More than unity

598. What is the SI unit of conductance?

# a) Sieman

b) Ohm

c) Ohm-metre



599. What is the SI unit of resistivity?

# a) Ohm metre

b) Ohms/metre

c) Ohms

600. Generator voltage is

# a) dependant on speed of rotation

b) independent of speed of rotation

c) not dependant on speed of rotation

601. If a negatively charged conductor is placed next to an insulated rod

a) the rod has no charge

b) the rod becomes negatively charged

# c) the rod becomes positively charged

602. What is the formula for conductance?

# a) 1/R

b) 1 - R

c) R + 1



603. What happens if you reverse the supply to the field and armature of a DC shunt motor?

a) Reverses direction of rotation

# b) Continues to rotate in same direction

c) Fails to start

604. The internal resistance of a battery off load compared to on load is

# a) same

b) increased

c) decreased

605. What is the rating of a monolithic capacitor with 103 on it

# a) 10000pf

b)100000pf

c) 1000pf

606. What is the formula for working out the capacitance of a capacitor if K = dielectric

constant, A = area of the plates, d = distance plates apart?

# a) c = KA/d

b) c = Kd/A

c) c = d/KA



607. 115V RMS 2.5A at 60 degrees what is the power disipated?

a) 79 W

# b) 143 W

c) 300 VA

608. If cobalt has a permeability of 4800 it is a

# a) ferromagnetic

b) paramagnetic

c) diamagnetic

609. The output from a generator to a commutator is

# a) AC

b) DC

c) pulsed DC

610. When light hits a photodiode resistance

a) increases

# b) decreases

c) stays the same



611. What type of wave is it when the vertical and horizontal distances are equal?

# a) Square

b) Rectangular

c) Sawtooth

612. Cobalt has permeability

# a) greater than unity

b) same as unity

c) less than unity

613. In an aircraft brushless alternator the armature is

a) in series with the field

# b) star wound

c) delta wound

614. to supply a 24 volt output with a transformer with a 5:1 turns ratio,

the input required is

# a) 120V

b) 4.8V

c) 24V



615. in a resonant parallel circuit, current is

a) max

# b) min

c) zero

616. Total capacitance of 3 capacitors each 12mF in a parallel circuit

# a) 36mF

b) 12mF

c) 6mf

617. Band stop filter

# a) attenuates frequencies in a specified narrow band

b) stops frequencies in a narrow band

c) pass all frequencies in that band

618. A combination of 1 megohm and 8 microfarad would give a time constant of

a) 40 seconds

# b) 8 seconds

c) 400 ms



619. Power factor is

a) sin theta

# b) cos theta

c) tan theta

620. What is the main disadvantage of a starter generator?

# a) Will not supply output at low rpm

b) Heavier than like for like

c) Can only be used on piston engines

621. What is the voltage across a fully charged capacitor?

# a) Same as circuit voltage

b) Less than circuit voltage

c) More than circuit voltage

622. When would you use an electrolytic capacitor?

a) On a balanced circuit

# b) Large output compared to size required

c) Low output compared to size required



623. If the phase voltage of a star wound generator is 115V, what would be the line-to-line

voltage?

# a) 200V

b) 180V

c) 220V

624. Back-EMF is the greatest when a motor is

# a) at operating speed

b) just starting to rotate

c) under heavy load

625. What are the factors affecting the frequency of an ac generator?

a) Number of turns in the armature coil and rpm

# b) Number of pole pairs and rpm

c) Number of turns in the armature coil and number of pole pairs

626. Which of the following applications would require a "continuously rated" motor

a) Flap drive actuator

# b) Fuel pump motor

c) Cargo door actuator



627. What would you use for the core in a generator current transformer?

# a) Air core

b) Laminated core

c) Steel Core

628. Spontaneous magnetisation occurs in a

a) permomagnet

# b) ferromagnet

c) diamagnet

629. An aircraft transformer is needed to step up a voltage. What sort would be used

a) Air core

# b)Laminated core

c) Solid core

630. A conductor is placed in a magnetised coil. What will happen

a) A force will be created

# b) Nothing will happen unless the conductor is moved

c) The conductor will move



631. An atom with less than 4 electrons in its outer shell has

# a) low electrical resistance

b) high electrical resistance

c) no electrical resistance

632. in a 4:1 step-up transformer, 120V is applied to the primary, and the load on the

secondary is 1600 Ohms. What is the current in the primary?

a) 0.075A

# b) 1.2A

c) 3A

633. Two 12V, 40Ah cells in series gives

# a) 24V 40Ah

b) 24V 80Ah

c) 12V 40Ah

634. A 2 Megohm resistor can be written

a) M20F

# b) 2M0F

c) 20MF



635. If a resistor is too small or misshapen to fit the colour code bands, how else is it's value

indicated?

a) Dots

# b) Letter code

c) Number code

636. Elements such as phosphorus with 5 electrons in their outer shell, when combined with

pure silicon, is a

# a) donor

b) acceptor

c) isotopic

638. A centrifugal speed switch is used

# a) to cut out the resistor/inductor circuit on an AC motor

b) to cut out the capacitor circuit on an AC motor

c) to cut in the resistor/inductor circuit on an AC motor

639. Disconnecting one of the phases from a 3-phase motor will cause the motor to

a) stop

# b) run a 2/3 speed

c) run at the same speed



640. To find the internal resistance of a battery in a circuit of known current

a) use the formula R = V x I

# b) find the lost volts of the circuit

c) find the EMF of the circuit

b2 module 3 test 2

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