Question

When an animal touches an ‘electric-fence’ the animal gets a shock by completing an electrical circuit.

1. Draw an equivalent circuit using symbols, which shows the completed electrical circuit. (Assume that the animal has a resistance)

2. How much charge passes through the animal, if it receives a current pulse of 20 mA for 0.1 seconds.

3. When a bird perches on the electric fence, the bird will not get a shock. Why?

Answer 1

1.

2. 1 = Q/t

Q = 1 × t = 20 × 10^-3 × 0.1 = 20 × 10^-4 C

3. Since the bird does not come in contact with the earth, its body is at same potential. So there is no potential difference and current. Hence the bird will not get a shock.