Science (086) — AI-generated practice question

Short-circuiting occurs when the live wire and the neutral wire come into direct contact (due to damaged insulation or a fault in an appliance). This causes the resistance in the circuit to drop drastically, and the current increases abruptly to a very high value.

Protection by fuse: An electric fuse is connected in series in the circuit. When the excessive current flows due to short-circuiting, the Joule heating effect melts the fuse wire, breaking the circuit. This stops the flow of unduly high current and prevents damage to appliances and wiring.

Source: Chapter 12, Section 12.4 — Domestic Electric Circuits

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• 3 marks are typically split: 1 mark for defining short-circuiting (direct contact of live and neutral → sudden rise in current), and 2 marks for explaining the fuse's role (series connection → Joule heating → fuse melts → circuit breaks → appliances protected).
• Always mention that the fuse is connected in series — examiners specifically look for this.
• The phrase "Joule heating melts the fuse" is key terminology from the textbook; use it exactly.
• Do not confuse short-circuiting (direct wire contact) with overloading (too many appliances or high supply voltage) — the question asks specifically about short-circuiting.