Q: A glass window conducts out a certain quantity of heat per second when the inside temperature is -10°C and the outside temperature is 10°C. The same quantity of heat will be conducted in through the window per second when the inside temperature is -43°C and the outside temperature is
(a) 43°C
(b) -23°C
(c) 23°C
(d) 0°C
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Ans: (b)
Sol: As , $\large i = \frac{\Delta T}{R}$
Let outside temperature is T°C
Hence , $\large \frac{10 -(-10)}{R} = \frac{T-(-43)}{R} $
20 = T + 43
T = -23°C