S1E1.5: Simple Power

 In the circuit shown:

the strength of the source is V, and the resistance of the resistor is .

The power dissipated in the resistor is given by the equation: P = IV

P = I * 10

What is I?

To discover I, we need to use Ohm's Law to calculate the current flowing through the resistor:

V = IR

V / R = I

I = V / R

I = 10 / 50 = 1 / 5 = 0.2A

P = 0.2 * 10 = 2 Watts

What is the power dissipated in the resistor (in Watts)? 2

To balance the 2 Watts leaving the source, we consider -2 W to be entering the source. Therefore the source has no net change in charge over time (per our Lumped Element Abstraction assumptions).

What is the power entering the source (in Watts)? -2