Ohms Law Manual

Ohm's law equation is a powerful predictor of the relationship between potential difference, current and resistance. The predominant equation which pervades the study of electric circuits is the equation V=I•R The Ohm's law equation can be rearranged and expressed as

The table below illustrates this relationship both qualitatively and quantitatively for several circuits with varying battery voltages and resistances. Battery

Total

Voltage

Resistance

Current

( V)

( )

(Amps)

1.

1.5 V

3

0.50 Amp

2.

3.0 V

3

1 Amp

3.

4.5 V

3

1.5 Amp

4.

1.5 V

6

0.25 Amp

5.

3.0 V

6

0.5 Amp

6.

4.5 V

6

0.75 Amp

Circuit Diagram

7.

Quantity

4.5 V

Symbol

Potential Difference

Equation(s)

9

Standard Metric Unit

Other Units

Volt (V)

J/C

V = PE / Q V

(a.k.a. voltage) Current

V=I•R I=Q/t I

Amp or C / s Amperes (A)

I= V/R P = PE / t Power

0.50 Amp

P

or V / Watt (W)

J/s

Ohm ( )

V/A

(more to come) R = • L/A Resistance

R R= V/I PE = V • Q

Energy

E or PE

V • C or Joule (J)

PE = P • t (Note the unit symbol C represents the unit Coulombs.)

W•s