Why is an electric fuse required in all electrical appliances?

Hint: Fuse is nothing but a circuit breaker. When there is an excess current across an electrical appliance the fuse gets melted and breaks the circuit. From this, we can conclude why we require a fuse in all the electrical appliances.

Complete step-by-step solution:
A fuse is a small piece of wire connected in series with the electrical appliances. This wire is chosen such that it melts when excess current passes through the electrical appliance. When excess current passes through the electrical appliance, it can damage the appliance permanently as well. Since the current in series remains the same, the fuse wire gets melted and breaks the circuit thereby protecting the appliance from getting damaged. Hence an electric fuse required in all electrical appliances for the protective reason of the appliance.

Note: For different electrical appliances we require different resistance of the fuse. The fuse wire is chosen such that it has a low melting point and for a particular value of current it melts thereby stopping the flow of excess current. We basically require a fuse because the voltage level that we receive in our homes keeps on fluctuating thereby resulting in an increasing and decreasing current.
 It is very much cumbersome to use fuses as we have to replace the fuse wire again and again when it is melted. Therefore nowadays fuses are replaced by MCB’s. These Miniature circuit breakers are designed such that the circuit becomes open when excess current is passed through any given circuit and closed when the current in the circuit is as expected.