JEE Main On 16 April 2018 Question 2
Question: A heating element has a resistance of $ 100\Omega $ at room temperature. When it is connected to a supply of 220V, a steady current of 2A passes in it and temperature is $ 500^{o}C $ more than room temperature. What is the temperature coefficient of resistance of the heating element? [JEE Main 16-4-2018]
Options:
A) $ 1\times {10^{-4}}{{,}^{o}}{C^{-1}} $
B) $ 5\times {10^{-4}}{{,}^{o}}{C^{-1}} $
C) $ 2\times {10^{-4}}{{,}^{o}}{C^{-1}} $
D) $ 0.5\times {10^{-4}}{{,}^{o}}{C^{-1}} $
Show Answer
Answer:
Correct Answer: C
Solution:
We know that resistance $ R=\frac{V}{i}=\frac{220}{2}=R _{o}(1+\alpha \Delta t) $
Also $ R _{o} $ is given as $ 100\Omega $
Putting $ \Delta T=500,K $ We get $ \alpha =2\times {10^{-4}} $
