a) When does a fuse cut off current? How does it do it? b) What is the maximum number of 60W bulbs that can be run from the mains supply of 220 volts if you do not want to overload a 5A fuse?

Answer:

a) When the current exceeds the safe limits, the fuse wire melts and breaks the circuit. This is called a fuse turned off.

b) Given,

V = 220V

I = 5A

Let the maximum number of bulbs be y

Power of y bulbs, P = 60y

As we know that,

P =VI

60y = 1100

y = 18.33

Therefore, the number of bulbs required is 18.