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