Answer:

a) Given in the question,

V = 6V

R1 = 1 ohm

R2 = 2 ohm

Thus, we get

Equivalent resistance of R1 & R2 in series,

R = R1 + R2

= 3 ohm

Total current, I = V/R = 6/3 = 2amp

Current through R2,

I2 = I = 2amp

Voltage across R2,

V2 = I2R2 = 4V

Power used in R2,

P2= I2V2 = 8W

b) Given in the question,

V = 4V

R1 = 12 ohm

R2 = 2 ohm

Voltage across R2,

V2 = V = 4V

Current across R2,

I2 = V2/R2

= 2 amp

Power used in R2,

P2= I2V2 = 8W