ohm's law   

OHM'S LAW
FACTOR WHAT? SYMBOL UNIT
VOLTAGE

- after Alessandro
Volta
- electrical pressure
- energy potential
- voltage is the difference in potential energy between two points in a circuit

 VOLTAGE
V
VOLTAGE		 V
volts
a measure of potential energy
(E)
     CURRENT
- discovered by Ampere
- rate of flow of electrons
- flow of current in a closed circuit due to application of a voltage
- measured in Coulombs per sec

- electrons flow from negative to positive
* 1 Coulomb is 6.24 x 1018  electrons
I
Intensity of current flow
CURRENT

 

  A
amps
- the rate of current flow
 RESISTANCE
- by Simon Ohm		  

 

 

 

- opposition to current flow

- indicates electrical energy is being converted into another energy form
R resistance
b
In AC it is called Impedance Z =
XL-inductive reactance
XC - capacitive reactance
 ......
ohms
measure of the opposition to current flow

 

Basic Ohm's Law  - states that
V= I x R I = V/R R = V/I

Example:

 If a light circuit has a source voltage of 120 V and a heater load of 6 ohms then the total current flowing would be ::
                                                            I = V/R   = 120V /6 ohms = 20 A (amps)

V = I x R  120 V R = V/I = 6 ohms I = V/R = 20 A

Ohm's Law example > 
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