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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 does not radiate heat

It radiates the same quantity of heat as it absorbs

It radiates less quantity of heat as it receives from surroundings

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

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 does not radiate heat

It radiates the same quantity of heat as it absorbs

It radiates less quantity of heat as it receives from surroundings

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

This test is of Physics and the chapter is Thermodynamics

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

1820 days 11 hours 6 minutes ago

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