A solid at temperature T1, is kept in an evacuated chamber at temperature T2 > T1 . The rate of increase of temperature of the body is proportional to
1. T2 – T1
2. \(T^2_2 -T^2_1\)n
3. \(T^3_2 -T^3_1\)
4. \(T^4_2 -T^4_1\)
The thermal radiation emitted by a body is proportional to Tn where T is its absolute temperature. The value of n is exactly 4 for
1. a blackbody
2. all bodies
3. bodies painted black only
4. polished bodies only.
Two bodies A and B having equal surface areas are maintained at temperatures 10°C and 20°C. The thermal radiation emitted in a given time by A and B are in the ratio
1. 1 : 1.15
2. 1 : 2
3. 1 : 4
4. 1 : 16.
One end of a metal rod is kept in a furnace. In steady state, the temperature of the rod
1. increases
2. decreases
3. remains constant
4. is nonuniform
Newton’s law of cooling is a special case of
1. Wien’s displacement law
2. Kirchoff 's law
3. Stefan’s law
4. Planck’s law.
1. a
2. b
3. c
4. d
A hot liquid is kept in a big room. The logarithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly
1. a straight line
2. a circular arc
3. a parabola
4. an ellipse.
A body cools down from \(65^\circ \text{C}\) to \(60^\circ \text{C}\) in \(5\) minutes. It will cool down from \(60^\circ \text{C}\) to \(55^\circ \text{C}\) in:
1. | \(5\) minutes |
2. | less than \(5\) minutes |
3. | more than \(5\) minutes |
4. | less than or more than \(5\) minutes depending on whether its mass is more than or less than \(1\) kg |
One end of a metal rod is dipped in boiling water and the other is dipped in melting ice.
(a) All parts of the rod are in thermal equilibrium with each other.
(b) We can assign a temperature to the rod.
(c) We can assign a temperature to the rod after steady state is reached.
(d) The state of the rod does not change after steady state is reached
Choose the correct option
1. (a) , (b)
2. (b) , (c)
3. (d) only
4. (a) , (d)
Which of the following actions does a blackbody not perform?
(a) Emit radiation
(b) Absorb radiation
(c) Reflect radiation
(d) Refract radiation
Choose the correct option from the given ones:
1. | (a) and (b) only |
2. | (b) and (c) only |
3. | (c) and (d) only |
4. | (a) and (d) only |