Practice portal › Current Electricity › Resistance and Resistivity

The resistance of a bulb filament is 100 Ω at a temperature of 100°C. If its temperature coefficient of resistance be 0.005 per °C, its resistance will become 200 Ω at a temperature of

Asked in JEE Main 2006 · Temperature dependence of resistance

• (1) 200°C
• (2) 300°C
• (3) 400°C
• (4) 500°C

Step-by-step solution

Why the other options are wrong

• (1) Reports the temperature rise Δ t=200°C from the approximate formula as the final temperature.
• (2) Uses R₂=R₁(1+αΔ t) with 100°C as the reference instead of 0°C.
• (4) No standard slip gives 500°C; with the correct R₀≈66.7 Ω at 0°C it would give R≈233 Ω, not 200 Ω.

Reading this solution needs no sign-in. You only sign in to practise against the clock and keep your progress.