Question

A battery and a resistor are wired into a circuit. The resistor dissipates 0.30 W. Now two batteries, each identical to the original one, are connected in series with the resistor. What power does it dissipate?

Answer 1

Answer:

1.2 W

Explanation:

Let the value of resistance be R , emf of battery be E

current i = E / R

power = i² R

= E² x R / R²

= E² / R

Given

E² / R = .30

when two batteries are connected

Total emf = 2E

current = 2E / R

Power = ( 2E / R )² x R

= 4 E² / R

= 4 x .30

= 1.2 W .