Question

What is the meaning of the statement "the current rating of a fuse is $5A$" ?

• A. Maximum $10A$ pass through it after it will melt.
• B. Maximum $5A$ pass through it after it will melt.
• C. Maximum $2A$ pass through it after it will melt.
• D. Maximum $1A$ pass through it after it will melt.

Answer 1

The correct option is B Maximum $5A$ pass through it after it will melt.

Fuses are safety devices that are to be built into our electrical system. If there were no fuses and we operated too many appliances on a single circuit, the cable carrying the power for that circuit would get extremely hot, short circuit, and possibly start a fire. To prevent electrical overloads, fuses are designed to trip or blow, stopping the flow of current to the overloaded cable.
Fuse is a piece of wire of a material with a very low melting point. When a high current flows through the circuit due to overloading or short circuit, the wires gets heated and melts. As a result, the circuit is broken and current stops flowing.
The fuse must always be connected to the mains and it must be of correct current rating. For example, a 15-ampere fuse should trip when the current through it exceeds 15 amperes. A 20-ampere fuse should blow when the current through it exceeds 20 amps.
Hence, the statement 'the current rating of a fuse is 5 A' means that the fuse should trip when the current through it exceeds 5 amperes. So correct option is B.