Electric heaters are made from a wire of:

Question

Electric heaters are made from a wire of:

1. A. Copper
2. B. Nichrome (Correct answer)
3. C. Constantan
4. D. Magnesium

Correct Answer

Option B — Nichrome

Detailed Solution & Explanation

The correct answer is Nichrome.

Key Points

• Electric heaters use nichrome, an alloy of nickel and chromium, for the heating element.
• Nichrome is chosen because it has high resistivity, a high melting point (about 1400°C) and does not oxidise readily when red hot.
• Copper has very low resistivity and is used for connecting wires, not heating elements.

Additional Information

• The heating follows Joule's law, H = I²Rt, so a high resistance produces more heat for the same current.
• The same reasoning explains why a fuse wire is made of a low-melting alloy of tin and lead, so that it melts first and breaks the circuit.
• Tungsten, with the highest melting point of any metal, is used for filaments in incandescent bulbs.