Electric Current

Electric currentElectric current is the rate of electron flow past a specific point in the circuit (how fast electrons pass through a point in the wire).

The symbol for electric current is I.

The units of electric current is amperes or amps (A).

Electric current

DC

Electric current

AC

Electric current can be compared to the flow of water.

Electric current can be compared to water current:

Comparison Water Current Electric Current

Conductor

What is flowing

Units for flowing particles

Time interval

Rate of flow (current)

pipe or hose wire

water molecules electrons

Litres (L) of waterCoulombs (C) of charge(1 C = amount of charge on 6.25x1018 electrons)per second (s) per second (s)

litres per second coulombs per second 1 ampere (A) = 1C/s

AMMETERS are used to measure the

________________ in a circuit.electric current

How to use an AMMETER

How to use an AMMETER

I0I0 the current coming from

the power source.

I1 the current passing through the bulb.

Example: We want to measure the current at I0 and I1 for the circuit below.

I1

To measure the current at I0 or I1, the circuit must

be _________________ to make the ammeter

part of the circuit. The ammeter is then

connected in _____________.

disconnected

How to use an AMMETER

series

Connect the terminal of

the ammeter to the wire(s) leading to the

___________________terminal of the power

source.

positive / red

How to use an AMMETER

positive / red

Connect the terminal of

the ammeter to the wire(s) leading to the

___________________terminal of the power

source.

negative / black

How to use an AMMETER

negative / black

How to use an AMMETERTo measure I0 :

How to use an AMMETERTo measure I1 :

How to Read an AMMETER

How to Read an AMMETER

What is the reading on this ammeter?

If you connected the circuit to the 3A setting on the ammeter, then the current reading is 1.5 A.

If you connected the circuit to the 1A setting on the ammeter, then the current reading is 0.5 A.

How to Read an AMMETER

What is the reading on this ammeter?

If you connected the circuit to the 3A setting on the ammeter, then the current reading is 2.15 A.

If you connected the circuit to the 1A setting on the ammeter, then the current reading is 0.72 A.

How to Read an AMMETER

What is the reading on this ammeter?

If you connected the circuit to the 300 mA setting on the ammeter, then the current reading is 215 mA.

Electric Shock