Question

Two resistors, 6 ohms and 18 ohms are connected in parallel and the combination is connected in series with a 2 ohm resistor. Find the current through each of the first two resistors if the current through the 2 ohm resistor is 1.2 ampere. What is the voltage across each resistor?

Answer 1

well first the 2 ohm resistor
Vtwo = i R = 1.2*2 = 2.4 volts

Now the two in parallel
They are both at voltage V
V = i1 (6) = i2 (18)
but we know i1+i2 = 1.2
so i1 = 1.2 - i2

6(1.2- i2)=18 i2
7.2 = 24 i2
i2 = 7.2/24 = .3 amps through 18 ohm
i1 = 1.2 - .3 = 0.9 amps through 6 ohm resistor

.9*6 = .3*18 = 5.4 volts across 6 and 18 ohm resistors