Question

In a safety fuse, the temperature to which the wire gets heated is directly proportional to the

• A. the square of the current
• B. the fourth power of the current
• C. the cube of the current
• D. none of these

Answer 1

The correct option is A

the square of the current

Explanation for the correct answer:

Option (A) the square of the current

1. Fuse is a safety device to protect electrical devices.
2. Fuse basically is made of small wire with high resistivity and low melting point.
3. It works on the principle of the heating effect of electric current and uses Joule's law of heating.
4. According to Joule's law of heating, the amount of heat produced is given by $H=I^{2}Rtjoules$; where I is the current in A, R is the resistance in $\Omega$ and t is the time for which the current is passed through the fuse.
5. We know that, $H\propto T$ where T is the temperature.
6. Thus, we can write $T\propto I^2$; i.e, Temperature $\propto$ square of the current.

Hence, option A is the correct answer.