Science (086) — AI-generated practice question

The metallic casing of an electric iron can conduct electricity. If a fault causes current to leak into the casing, the earth wire provides a low-resistance path to the earth, keeping the casing's potential equal to earth potential, thus preventing a severe electric shock to the user.

A plastic body is a poor conductor (insulator), so even if current leaks internally, it cannot flow through the plastic casing to the user. Hence, no earth connection is needed.

Source: Chapter 12, Section 12.4 – Domestic Electric Circuits

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• The key concept is conductivity: metals conduct, plastics insulate.
• The earth wire's role is to provide a low-resistance path so leakage current flows to earth rather than through the user.
• Examiners expect you to explain why metal needs earthing (shock hazard) and why plastic doesn't (non-conductor = no shock risk). Both parts needed for full 2 marks.