ELECTRICAL CURRENT

ELECTRICAL CURRENT

• Atoms are in everything and are made up of equal amounts of positive and negative charges.

Types of Electrical Current

• Alternating current moves the impulse back and forth

• 1 cycle/sec is called a HERTZ

• Household current is 60 Hz.

Alternating current

• Type of current that enters your home

• Economical in being transported from power plant to home….. Less energy loss to friction.

A Safety Fuse protects your house from too much electrical current

Direct current

• Electricity flows directly from the negative [cathode] to positive [anode] terminals

• Less electricity loss due to friction

• Used in electronics

• Supplied by batteries and generators

Direct Current

• Direct current can be compared to the flow of water

Comparing Different Batteries

What is the difference in a D cell and an AA cell?

Important electrical terms

• VOLTAGE

• CURRENT

• RESISTANCE

VOLTAGE

• Electrical potential energy per charge • Measured in volt or joules/ coulomb• Referred to as “potential difference”• When generated by battery or

magnetic force, it is called electromagnetic force.

Voltage

• The force-like quantity that moves a coulomb of electrons

• The greater the voltage, the greater the flow of electrical current for the

same resistance

Current=I

•Flow of electrons through a conductor

•Measured in Amperes [Amps]

•1 amp= 1 coulomb/sec

Resistance

RESISTANCE [Ω]

• Measured in OHMS or Ω• One ohm= one volt/one amp• Depends of the type of conductor [i.e.

gold has a very low resistance while tungsten has a very high resistance]

• Insulators have extremely high resistance

• An increase in temperature will increase the resistance

RESISTORS

Multi-functional Digital Meter

CURRENT ELECTRICITY

TERM SYMBOL UNIT SYMBOL

VOLTAGE V VOLT= JOULE/COULOMB

V

CURRENT I AMP= COULOMB/SEC

A

RESISTANCE R OHM= VOLT/AMP

Ω

Electrical Work

• Work = voltage X charge

•W=Vq

•Unit for work = joule

Electrical Power

• Power = current X volts

• VI=P

• Unit for power = watt

SERIES CIRCUIT

SERIES CIRCUIT

Series Circuit-current• The total current

in a series circuit is equal to the amount of current that passes through the greatest resistor or load

Series Circuit-voltage

• Total Voltage is equal to the sum of the individual voltages in the circuit.

1.5V

0.5V

0.5V

0.5V

SERIES CIRCUIT

RESISTANCE

The total resistance in this circuit is equal to the SUM of the resistance in each resistor.

V=10x6 = 60V

V= 5x6 = 30V

6 amps

CURRENT

FLOW HERE

15 amps

TOTAL RESISTANCE

PARALLEL CIRCUITS

• More than one connection at each resistor or load

Parallel Circuits-Current

• The total current in a parallel circuit is equal to the sum of the current through each resistor.

Parallel Circuit-Voltage

• In a parallel circuit, the voltage is equal through out the entire circuit.

Parallel Circuit-Resistance

• The total resistance in a parallel circuit is always less than the least resistor in the system

Rt<1

Parallel Circuits

How is “electricity generated” or

“electricity and magnetism”?

Current and Magnetism

• The magnetic field lines around a long wire which carries an electric current form concentric circles around the wire. The direction of the magnetic field is perpendicular to the wire and is in the direction the fingers of your right hand would curl if you wrapped them around the wire with your thumb in the direction of the current.

Current and magnetism

• The right-hand rule helps us keep our direction straight…..

Electromagnets vs. Permanent

These three factors all increase the strength of an electromagnet:

•Increasing the current flowing through the coil

• Increasing the number of coils

• Putting a core of a magnetic material inside the solenoid. The iron core becomes magnetized itself and makes the field stronger.

Current and Magnetism

• If a wire is moved through a magnetic field, an electrical current is produced.

• This is an example of a generator

• If a current carrying wire is in a magnetic field then a force is produced. This is an example of a motor.

The electric Motor

http://www.walter-fendt.de/ph11e/electricmotor.htm

Generating Electric Current requires a magnetic field and the movement of a metal wire through the field

An Electric MOTOR can be an Electric Generator if it is turned by a mechanical force.

Solar Panels convert SUNLIGHT into ELECTRICITY

The Future of Transportation