Calculate the power used in the 2Ω resistor in each of the following circuits: a) a 6V battery in series with 1Ω and 2Ω resistors a 4V battery in parallel with 12Ω and 2Ω resistors

1. Given, V = 6V

R1 = 1 ohm R2 = 2 ohm

Equivalent resistance, R = R1 + R2 = 3 ohm Total current, I = V/R = 6/3 = 2amp

Current through R2 = I2 = I = 2amp Voltage across R2 = V2 = I2R2 = 4 ohm Power used in R2 = I2V2 = 8W

b) 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 = I2V2 = 8W