electric current. there are 72 names of french mathematicians, engineers and scientists on the side...

Electric Current

There are 72 names of French mathematicians, engineers and scientists on the side of the Eiffel tower

Electric Current (I)

The flow of electric charge

Unit- Amperes (Symbol A)

An Ampere - 1 coulomb of charge second (1 coulomb = 6.24 billion billion electrons)

Measured using an ammeter

Electric Current

When no electricity is applied…free electrons (conducting electrons) are always moving in random motion

But when the switch is closed the free electrons of the conductor are forced to drift toward the positive terminal under the influence of the electric field

Resistance

Resistance- helps to control the amt of current

Opposition to the passage of an electric current through that conductor.

Unit-  ohm (Ω)

Resistance (R)

The resistance of an object depends primarily on 3 factors:

1) What the material is made of

Place in order of least resistance the following materials:

Aluminum, gold, silver,

glass, copper

SilverCopperGoldAluminumGlass

The resistance of an object depends primarily on 3 factors:

2) It’s thickness A thick copper wire has lower resistance than an otherwise-identical thin copper wire.

Not a good idea

3) It’s length For example- a long copper wire has higher resistance than a short copper wire. 

Relationship between voltage, current and resistance

Ohm’s Law

Ohm’s Law

Current = Voltage

Resistance

Current (amps)= Voltage (volts)

Resistance (ohms)

The greater the voltage the _ the current

The greater the resistance the _ the current

Resistance

A typical lightbulb has a resistance of 100 Ώ

An iron or toaster has a resistance of 15-20 Ώ

The lower resistance permits a large current, which produces a considerable amount of heat