beath high school - int 1 physics1 intermediate 1 physics electronics questions and answers

Beath High School - Int 1 Physics 1

Intermediate 1 Physics

Electronics

Questionsand

Answers


Intermediate 1 Physics

ElectronicsQ 1 to 9

Q 10 to 18


1. Describe what is meant by an electronic system. Give two examples

An electronic system is made up from lots of electronic components to do a particular job.Two examples of electronic systems are a calculator and a public address system.

Electronic Systems


2. The block diagram for a calculator is shown below.Identify the input, process and output subsystems.

Input Process

Keypad CalculatingCircuits

Display

Output


3. Draw a block diagram of each of the following systems. Identify the input, process and output subsystems in each case.

(a) A public address system

(b) A smoke alarm

amplifier loudspeaker

I nput OutputProcess

microphone

logic circuits

buzzer


smoke sensor


(c) An automatic porch light (lamp lights when it gets dark)

(d) An automatic fan (fan operates when it gets too warm)

logic circuits

bulb


light sensor

logic circuits

motor


temperaturesensor


(e) A radio.

amplifier loudspeaker


aerial


4. What is sensed by each of the following input devices

(c) light dependent resistor

(b) thermistor

(a) microphone

(d) switch

sound

heat

light

pressure


5. What can change the resistance of a thermistor?

As the light level increases the resistance decreases

6. State how the resistance of a light dependent resistor changes with light level.

Change in temperature

7. Describe an experiment you would perform to determine how the resistance of a thermistor changes with temperature.

Connect a thermistor to a resistance meter and heat the thermistor gently with your fingers. Watch what happens to the resistance on the meter.


8. Describe an experiment you would perform to determine how the resistance of a light dependent resistor changes with light level

Connect the microphone to the input of the oscilloscope. Speak into the microphone. You will see a wave pattern on the screen which matches your voice.

9. Describe how you would use an oscilloscope to examine the output signal from a microphone. Describe what is seen on the oscilloscope screen.

Connect a LDR to a resistance meter and cover it over with your hand. Watch what happens to the resistance on the meter.


10. Describe the energy changes which take place in the following output devices:

electrical energy to light energy

loudspeaker

buzzer

lamp

light emitting diode (LED)

electric motor

electrical energy to sound

energy

electrical energy to sound

energy

electrical energy to light energy

electrical energy to kinetic

energy


11. Study the circuit symbols below. In each case:(a) name the device(b) state whether it is an input or output device(c) state the energy changes in the device(d) give an example of where it could be used

device 1

(a) microphone

(b) input device

(c) sound energy to electrical energy

(d) input to a public address system


device 2

(a) buzzer(b) output device(c) electrical energy to sound energy(d) warning device on a freezer, if

temperature inside rises above a particular temperature

device 3

(a) motor(b) output device(c) electrical energy to kinetic energy(d) output for a room cooling system

+

M


device 4

(a) thermistor

(b) input device

(c) heat energy to electrical energy

(d) input device on a freezer, to check temperature inside does not rises above a particular temperature

device 5

(a) light emitting diode(b) output device(c) electrical energy to light energy(d) indicates that something is switched on


device 6

(a) lamp(b) output device

(c) electrical energy to light energy

(d) output device for an automatic light which switches on when it gets dark

device 7

(a) loudspeaker(b) output device(c) electrical energy to sound energy(d) output device for a radio, so that we

can hear the music.


device 8

(a) light dependent resistor

(b) input device

(c) light energy to electrical energy

(d) input device for an automatic light which switches on when it gets dark

12. In the applications below identify which of the devices in Q 11 would be suitable. Give a reason for the choice of each device.

(a) Output of a radio

Loudspeaker, it changes the electrical energy form the amplifier to sound energy


(b) Input of an automatic lampLDR, because its resistance changes as the light level changes

(c) Input of a heating controllerThermistor, because its resistance changes as the temperature changes

(d) Output of a fan

Motor, because it will turn the fan.

(e) Output of an electronic timerLight emitting diode, it can form the part of a seven segment display to show the numbers.(f) Input of a cassette recorder – recorder

subsystemMicrophone, it will pick up the sound to be recorded.


(g) Output of a cassette recorder – drive subsystem.

Motor, it will turn the spindles.(h) Output of a cassette recorder – play back system

Loudspeaker, it will change the electrical energy back into sound energy.

13. Describe what is meant by a “digital signal”.

A digital signal is either on or off


14. Draw an oscilloscope trace of a digital signal


15. Draw the symbol for each of the following logic

gates:(a) NOT gate or Inverter

(b) AND gate

(c) OR gate


16. The following is a truth table for a logic gate.

A NOT gate or inverter

(a) Name the logic gate.

(b) Explain in terms of voltage levels, what is meant by the “1”s and “0”s.

InputOutput

0

0

1

1

“1” is a high voltage, “0” is a low voltage


17. For each of the logic gates shown below:

(a) Name the gate(b) Draw the truth table(c) Describe the operation of the gate in words.

(a) NOT gate or inverter

(c) The output of the NOT gate is always the opposite of the input

Gate 1 InputOutput

0

0

1

1

(b)


(a) AND gate

(c) The AND gate combines the input signals so that the output is only 1 when both inputs are 1.

Input B

Output

0 0

1

1

(b)Input A

0

0

0

0

01

1 1

Gate 2

A

B


(a) OR gate

(c) The output of an OR gate is ‘1’ when any input is ‘1’.

Input B

Output

0 0

1

1

(b)Input A

0

1

1

0

01

1 1

Gate 3

A

B


18. The system below is designed to allow water to be sprayed on to plants if the air becomes too hot or the gardener switches the sprayer on.

(a) Name the logic gate used in the system.

Thermistor

Heat sensor1 = hot 0 = cold

Motor to operate sprayer

switch

A

B

(b) The gardener switches the the sprayer on. What is the logic level at B?

(c) What input device could be used in the heat sensor?

OR gate

Logic 1


Intermediate 1 Physics Electronics

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beath high school - int 1 physics1 intermediate 1 physics electronics questions and answers

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