Science (086) — AI-generated practice question

Tungsten for bulb filaments: Tungsten has a very high melting point (3380°C). When current flows, it generates a large amount of heat (Joule's heating). This heat raises the filament to very high temperatures, causing it to emit light. Since tungsten does not melt at such temperatures, it is ideal. However, this same property — converting most electrical energy into heat — makes it unsuitable for transmission lines, where energy loss is undesirable.

Copper/Aluminium for transmission lines: Copper and aluminium have very low resistivity, so they produce minimal heat (low energy loss) when current passes through them. This ensures efficient transfer of electrical energy over long distances with negligible wastage.

Source: Chapter 11, Section 11.7.1 (Practical Applications of Heating Effect of Electric Current)

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• The key contrast is high resistivity + high melting point (tungsten) vs low resistivity (copper/aluminium).
• For a filament: high resistance → more heat → light emission; high melting point → doesn't melt.
• For transmission: low resistance → less heat loss → efficient energy transfer.
• Examiners expect you to use the term Joule's heating and mention melting point for tungsten and low resistivity/resistance for copper/aluminium. These are the scoring keywords.