A circuit with a resistance of 3 Omega has a fuse with a capacity of 4 A. Can a voltage of 2 V be applied to the circuit without blowing the fuse?

1 Answer
Jan 23, 2016

The current in a circuit where a voltage of 2 V passes through a resistance of 3 Omega is given by: I=V/R = 2/3 A. This is well short of the capacity of the fuse, so the fuse will not blow.

Explanation:

Ohm's Law relates voltage V (V), current I (A) and resistance R (Omega):

V=IR

In this case we want to know the current, so we rearrange to make I the subject:

I=V/R = 2/3 A

The current flowing in the circuit is 2/3 A. A fuse is designed to 'blow' (burn out) if the current in the circuit is more than its rated value, in this case 4 A. This is to protect the rest of the circuit from excessive current which generates heat.

The current in this circuit, 2/3 A, is considerably less than 4 A, so the fuse will not blow.