An electric fuse is a safety device inserted in series with an electrical circuit. The operation of a fuse is based mainly on which effect of electric current?

Introduction / Context:

Electric fuses are widely used in household wiring and electrical appliances to protect circuits from excessive current. When a fault or overload occurs, the fuse blows and cuts off the supply, preventing damage or fire. This question asks which basic effect of electric current is used in the working of a fuse.

Given Data / Assumptions:

• A fuse is made of a thin wire or strip with low melting point material.
• It is connected in series with the circuit it protects.
• During overload, current becomes higher than the rated value.

Concept / Approach:

When electric current passes through a conductor, it can produce several observable effects. These include heating effect, magnetic effect, chemical effect, and in some cases light. A fuse relies on the conductor becoming hot when current exceeds a safe value. The heat generated is proportional to I^2 * R * t, where I is current, R is resistance, and t is time. If the temperature rises above the melting point of the fuse material, the fuse element melts and opens the circuit. No chemical reaction or magnetic field is required for this basic operation, so the key effect is the heating effect of current.

Step-by-Step Solution:

Verification / Alternative check:

In contrast, the magnetic effect of current is used in devices such as electromagnets and electric motors. The chemical effect is used in electroplating and electrolysis. Since a fuse does not rely on magnetism or chemical reactions, the heating effect is the only reasonable choice.

Why Other Options Are Wrong:

Option A: The chemical effect of the current appears in electrolysis, not in a fuse.

Option B: The magnetic effect is used in relays and motors, not as the main principle in a simple fuse wire.

Option D: The luminous effect of the current is observed in bulbs and discharge tubes where light is emitted, which is not the primary principle behind a fuse.

Common Pitfalls:

Sometimes students see the small flash of light when a fuse blows and incorrectly associate it with the luminous effect. However, that flash is a side effect of intense heating and melting, not the working principle. Always focus on the fact that the fuse is designed to melt due to heating when current becomes excessive.

Final Answer:

The operation of an electric fuse is based on the heating effect of the current.