Question

How much current is in one of the 10 W resistors in the diagram shown above?

Answer 1

First, find the equivalent resistance on the parallel circuit:

1/ Req = 1 /20 + 1/10 + 1/10

1 / req = 1/4

4 = r eq

r eq = 4 ohm

The add to the series resistance

Rt = 2 + 4 = 6 ohm

Apply Ohm's law:

V = I x R

I = V / R

I = V/R= 12 / 6 = 2 A

In series circuits, the current is the same,

Vtot= Vr1 + Vr2

Vr1 = I1 * R1 = 2 * 2 = 4 V

Vt = Vr1 + Vr2

Vr2= Vt-Vrq = 12 - 4 = 8 V

Apply ohm's law for each resistance:

I = Vr2 /R

I = 8 /10 = 0.8A