Question

Which of the following is not a safety measure commonly used in electric circuits.
(A) An electric fuse is connected in parallel
(B) Proper earthing of all electric circuit is done
(C ) Fuse protects the circuits from overloading
(D) All

Answer 1

A fuse wire is used in an electrical circuit to control the current flow. That is, a fuse wire acts as a safety device in electrical circuits and it can protect the household electrical devices from the damage caused due to the high flow of current. Thus we know that current and resistance are inversely proportional. Hence to decrease the very high current flow by increasing the resistance.

Complete step-by-step solution:
A fuse wire is usually made of materials which have high resistance and low melting point. So that it can prevent the amount of current flowing through the fuse wire. And the low melting point condition is very useful for a fuse wire because when large amount of current flows through the wire it melts the wire as high heat is generated. These two characteristics of the fuse wire helps to prevent the damage of household electrical appliances. The fuse wire is generally made up of materials which have high conductivity or low resistivity. For example, aluminium and tin. Thus we can say that fuse acts as safety device, because it can control the overcurrent passing through the wire. Now a days circuit breaker is an alternative used instead of a fuse wire.
An electric fuse which acts as a safety device is never connected in parallel. That is, a fuse is always connected in series.
Therefore option (A) is correct.

Note: The fuse is connected in series with the flow of current. At the time of current flow the resistance produces heat. When the amount of current is too large the heat produced will become very high and as a result fuse wire melts.