Q. A clock with an iron pendulum keeps correct time at 15$℃$. What will be the error, in second per day, if the room temperature is 20$℃?$ (The coefficient of linear expansion of iron is 0.000012$℃^{- 1}.)$
A) 2.6 s
B) 6.2 s
C) 1.3 s
D) 3.1 s
Explanation
(a) Here, $\mathrm{\Delta}T = 20 - 15 = 5℃$
$\alpha = 0.000012℃^{- 1} = 12 \times 10^{- 6}℃^{- 1}$
Time lost per day = $\frac{1}{2}\alpha(\mathrm{\Delta}T) \times 86400\ s\ $
=$\frac{1}{2}\ \times 12 \times 10^{- 6} \times 5 \times 86400\ s = 2.590\ s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.