Question

an energy source forces a constant current of 2.5amps for 20 seconds to flow through a light bulb. if 3kilojoules is given of in the form of light and heat energy calculate the charge of the current and the voltage drop across the bulb.

Answer 1

The amount of charge

$$q=It=2.5*20=50\:\rm C$$

The voltage drop

$$V=\frac{W}{q}=\frac{3000}{50}=60\:\rm V$$