Basic Electrical Theory
UNITS OF ELECTRICAL MEASUREMENT
3.
Resistance of a circuit is equal to the applied voltage divided by the circuit current.
Equation (1-4) is a mathematical representation of this concept.
(1-4)
R (or W)
E
I
where
I = current (A)
E = voltage (V)
R = resistance (W)
If any two of the component values are known, the third can be calculated.
Example 1:
Given that I = 2 A, E = 12 V, find the circuit resistance.
Solution:
Since applied voltage and circuit current are known, use Ohm’s Law to solve for
resistance.
R
E
I
R
12 V
2 A
6 W
Example 2:
Given E = 260 V and R = 240 W, what current will flow through a circuit?
Solution:
Since applied voltage and resistance are known, use Ohm’s Law to solve for
current.
I
E
R
I
260 V
240 W
1.083 A
Rev. 0
Page 15
ES-01
