Forty calories of heat is needed to raise the temperature of 1 mol of an ideal monatomic gas from 20°C to 30°C at a constant pressure….

Q: Forty calories of heat is needed to raise the temperature of 1 mol of an ideal monatomic gas from 20°C to 30°C at a constant pressure. The amount of heat required to raise its temperature over the same interval at a constant volume (R = 2cal mol-1K-1) is

(a) 20 cal

(b) 40 cal

(c) 60 cal

(d) 80 cal

Ans: (a)

Three rods of material ‘x’ and three rods of material y are connected as shown in figure. All the rods are of identical length and cross-section.

Q: Three rods of material ‘x’ and three rods of material y are connected as shown in figure. All the rods are of identical length and cross-section. If the end A is maintained at 60°C and the junction E at 10°C, find effective Thermal Resistance. Between A and E, Given length of each rod = l, area of cross-section = A, conductivity of x = K and conductivity of y = 2K.

Numerical

(a) \displaystyle \frac{4l}{3 K A}

(b) \displaystyle \frac{7l}{6 K A}

(c) \displaystyle \frac{4 K A}{3 l}

(d) \displaystyle \frac{7 K A}{3 l }

Ans: (b)

Assuming the sun to be a spherical body of radius R at a temperature ‘T’ K, evaluate the total radiant power….

Q: Assuming the sun to be a spherical body of radius R at a temperature ‘T’ K, evaluate the total radiant power incident on earth, at a distance r from the sun. (Take r0 is radius of earth ‘s’ Stefan’s constant)

(a) \displaystyle  \frac{4\pi {r_0}^2 R^2 \sigma T^4}{r^2}

(b) \displaystyle  \frac{\pi {r_0}^2 R^2 \sigma T^4}{r^2}

(c) \displaystyle  \frac{4\pi {r_0}^2 R^2 \sigma T^4}{4\pi r^2}

(d) \displaystyle  \frac{ R^2 \sigma T^4}{r^2}

Ans: (b)