notation
R34 is equivalent R of R3 and R4
R34 = R3 + R4 = 2 + 4 = 6
1/R234 = 1/R2 + 1/R34 = 1/6 + 1/6
R234 = 6/2 = 3
R1234 = 7 + 3 = R1 + R234 = 10
I1 = V/R1234 = 10/10 = 1
Vr1 (v across r1) = I1R1 = 1x7 = 7
loop law : V, R1, and R2
V - Vr1 - Vr2 = 0
Vr2 = 10 - 7 = 3
I2 = Vr2/R2 = 3/6 = 0.5
current law : R1, R2 and R3
I1 - I2 - I3 = 0
I3 = 1 - 0.5 = 0.5
I4 = I3
Vr3 = I3R3 = 0.5x2 = 1
Vr4 = I4R4 = 0.5x4 = 2
power dissipated = I1V = 1x10 = 10 watt
energy dissipated = pt = 10x0.5 = 5 watt/hour
