Working of safety fuses depends upon 1. magnetic effect of the current 2. chemical effect of the current 3. magnitude of the current 4. heating effect of the current Select the correct answer using the code given below.

The working of a safety fuse is primarily based on the heating effect of electric current and the magnitude of the current flowing through it. A fuse consists of a wire with a specific melting point placed in series with a circuit [1]. When the magnitude of the current exceeds the fuse's rated value, the temperature of the wire increases due to Joule heating (P=I²R) [3]. This heating effect causes the fuse element to melt, thereby breaking the circuit and preventing damage from overloading or short-circuiting. The time required for the fuse to blow is inversely proportional to the magnitude of the excessive current; higher currents lead to faster melting. While electric currents can produce magnetic and chemical effects, these are not the principles upon which a standard safety fuse operates [3]. Therefore, only the magnitude and heating effect are relevant to its function.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 11: Electricity > 11.7.1 Practical Applications of Heating Effect of Electric Current > p. 190
2. [3] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 4: Electricity: Magnetic and Heating Effects > Snapshots > p. 58