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The specific heat capacity of a substance is temperature dependent and is given by the formula C=kT, where k is a constant of suitable dimensions in SI units, and T is the absolute temperature. If the heat required to raise the temperature of 1 kg of the substance from -73 to 27 is nk, the value of n is . [Given: 0 K=-273 .]
25000
T1=200 K, T2=300 K.
Q=m T1T2kT dT=1 k2(3002-2002).
Q= k2(90000-40000)=25000k.
Answer: 25000
As shown in the figure, an insulated container is fitted with a thermally conducting but immovable partition (P1) and a freely movable but thermally insulated piston (P2). The partition P1 with thermal conductivity K, cross sectional area A and width x divides the container into two sections, S1 and S2, each containing one mole of a monoatomic gas. The piston P2 moves freely such that the gas in S2 is always at the atmospheric pressure. Initially, the difference between the temperatures of S1 and S2 is T0. The time it takes for the temperature difference to become T02 is nxR/KA, where R is the universal gas constant. The value of n is: [ Given: 2 0.7 ] [figure]
Two identical plates P and Q, radiating as perfect black bodies, are kept in vacuum at constant absolute temperatures TP and TQ, respectively, with TQ<TP, as shown in Fig. 1. The radiated power transferred per unit area from P to Q is W0. Subsequently, two more plates, identical to P and Q, are introduced between P and Q, as shown in Fig. 2. Assume that heat transfer takes place only between adjacent plates. If the power transferred per unit area in the direction from P to Q (Fig. 2) in the steady state is WS, then the ratio W0WS is [figure]