The potential difference across a lamp is 12V. How many joules of electrical energy are changed into heat and light when: a) a charge of 1C passes through it? b) a charge of 5C passes through it? a current of 2A flows through it for 10s?

Given,

Potential difference = 12V

1. Potential difference = (work done)/(charge moved) Work done = Potential difference × charge moved

= 12 × 1 = 12J

Therefore, 12J of electrical energy is converted into heat and light.

1. Work done = potential difference × charge moved

= 12 × 5 = 60J

Therefore, 60J of electrical energy is converted into heat and light.

1. I = Q/t Q = I × t

= 2 × 10 = 20C

Work done = potential difference × charge moved

= 12 × 20 = 240J

Therefore, 240J of electrical energy is converted into heat and light.