# Thermodynamics test of K-11 level

Two spheres made of same material have radii in the ratio 1: 2 Both are at same temperature. Ratio of heat radiation energy emitted per second by them is ____.
1 : 2
1 : 8
1 : 4
1 : 16
If the temperature of a hot body is increased by 50% then the increase in the quantity of emitted heat radiation is ____.
125 %
200 %
300 %
400 %
A black body at a temperature of 127°C radiates heat at the rate of 1 cal/cm2 ( sec. At a temperature of 527°C the rate of heat radiation from the body in (cal /cm2 ( s) is ____.
16.0
10.45
4.0
2.0
A black body radiates 20 W at temperature. If temperature of the black body is changed to  then its radiating power is ____.
120W
240 W
320 W
360 W
Two spheres of same material have radius 1m and 4 m and temperature 4000 K and 2000K respectively. The energy radiated per second by the first sphere is ____.
greater than that by the second
less than that by the second
equal in both cases
The information is incomplete
The radiation emitted by a star A is 10,000 times that of the sun. If the surface temperatures of the sun and the star A are 6000 K and 2000 K respectively, the ratio of the radii of the star A and the sun is ____.
300 : 1
600 : 1
900 : 1
1200 : 1
A black body radiates at the rate of W watts at a temperature T. If the temperature of the body is reduced to T/3, it will radiate at the rate of (in Watts) ____.
A sphere at temperature 600K is placed in an environment of temperature is 200K. Its cooling rate is H. If its temperature reduced to 400K then cooling rate in same environment become ____.
Rate of cooling at 600K, if surrounding temperature is 300K is R. The rate of cooling at 900K is ____.
A black body of surface area 10cm2 is heated to 127°C and is suspended in a room at temperature 27°C. The initial rate of loss of heat from the body at the room temperature is ____.
2.99 W
1.89 W
1.18 W
0.99 W
Two identical objects A and B are at temperatures TA and TB respectively. Both objects are placed in a room with perfectly absorbing walls maintained at temperatures T . The objects A and B attain temperature T eventually which one of the following is correct statement?
‘A’ only emits radiations while B only absorbs them until both attain temperature
A loses more radiations than it absorbs while B absorbs more radiations that it emits until temperature T is attained
Both A and B only absorb radiations until they attain temperature T
Both A and B only emit radiations until they attain temperature T
When the body has the same temperature as that of surroundings?
It radiates the same quantity of heat as it absorbs
It radiates more quantity of heat as it receives heat from surroundings
The ratio of radiant energies radiated per unit surface area by two bodies is 16 : 1, the temperature of hotter body is 1000 K, then the temperature of colder body is ____.
250 K
500 K
1000 K
62.5 K
If the temperature of the body is increased by 10%, the percentage increase in the emitted radiation is ____.
46 %
40 %
30 %
80 %
If the sun’s surface radiates heat at . Calculate the temperature of the sun assuming it to be a black body  ____.
A body cools in 7 minutes from  to  What time (in minutes) does it take to cool from  to  if the surrounding temperature is ? Assume Newton’s Law of cooling holds ____.
3.5
11
7
10
A body takes 5 minutes for cooling from  to  Its temperature comes down to  in next 5 minutes. Temperature of surroundings is ____.
The temperature of a body falls from to  in 10 minutes. If the temperature of the surroundings is Then temperature of the body after another 10 minutes is ____.
It takes 10 minutes to cool a liquid from 61oC to 59oC. If room temperature is 30oC then time taken in cooling from 51oC to 49oC is ____.
10 min
11 min
13 min
15 min
In Newton's experiment of cooling, the water equivalent of two similar calorimeters is 10 gm each. They are filled with 350 gm of water and 300 gm of a liquid (equal volumes) separately. The time taken by water and liquid to cool from  to  is 3 min and 95 s respectively. The specific heat of the liquid is ____.
0.3 Cal/gm (°C
0.5 Cal/gm (°C
0.6 Cal/gm (°C
0.8 Cal/gm (°C
Description:

This test is of Physics and the chapter is Thermodynamics

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Discussion

Two bodies A and B are kept in a vessel at 27°c.The temp. Of A is 527°c and temp of B is 127°c. Compare the rate at which heat is lost from A to B

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