On which of the following effects of electric current a fuse operates?

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Heating effect Explanation: An electric fuse operates on the thermal (heating) effect of electric current. It acts as a safety device in an electrical circuit by breaking the connection when excessive current flows, thereby preventing damage to equipment. Working Principle: When current flows through the fuse element, it generates heat proportional to the square of the current ($H = I^2Rt$). If the current exceeds the rated value, the heat generated exceeds the melting point of the fuse material. The fuse wire melts, creating an open circuit and disconnecting the supply. Key Formulas: $H = I^2 Rt$ — The heat produced in a conductor due to electric current flow. Key Points: A fuse is a low-melting point alloy wire typically made of lead and tin.; It is connected in series with the live wire of a circuit.; The process of melting the fuse wire is called 'blowing' the fuse.; The fuse protects against both overloads and short-circuit faults. Advantages: Low cost and simple design.; Provides reliable protection against short circuits.; Acts instantaneously under high-fault conditions. Disadvantages: Requires manual replacement after operation.; Probability of physical deterioration over time.; Cannot be used for automatic circuit reclosing. Applications: Domestic wiring and distribution boards.; Protection of electronic circuits and appliances.; Automotive electrical systems. Additional Info: The choice of material depends on the conductivity and the melting point required for specific current ratings.. Option A (Photoelectric) involves light-to-electron conversion; Option B (Electrostatic) involves stationary charges; Option D (Magnetic) involves current-induced fields (used in Circuit Breakers/Relays). Answer: C is correct — A fuse functions based on the heating effect of current, where Joule heating causes a low-melting-point wire to melt during an overcurrent event. Exam Tip: Remember that while Fuses operate on the Heating effect, Miniature Circuit Breakers (MCBs) typically utilize both Thermal (Heating) and Magnetic effects for protection.

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