A pendulum clock loses 12 s a day if the temperature is 400 C and gains 4s a day if the temperature is 200C. The temperature at which the clock will show correct time, and the co – efficient of linear expansion (a) of the metal of the pendulum shaft are respectively
12α(40−T)×86400=12s. . . .(1)12α(T−20)×86400=4. . . .(2)
On dividing (1) by (2) and solving
T=25∘C