ISC Physics Class XI Part 1>Chapter 25 - Thermal Radiation>NUMERICALS>Q 17

MEDIUM

11th ICSE

IMPORTANT

Earn 100

The temperature of black body is $727 ° C$ and its surface area is $0.1 m^{2}$ How many calories the body is emitting per minute.

Important Questions on Thermal Radiation

HARD

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 25 - Thermal Radiation>NUMERICALS>Q 18

The temperature of a filament of a lamp is

2450 K

. Its effective area is

0.048 {cm}^{2}

and its emissivity is

0.30

. Find the wattage of the lamp.

HARD

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 25 - Thermal Radiation>NUMERICALS>Q 19

The temperature of filament of

40 W

bulb is

2284 ° C

and its effective area is

0.66 {cm}^{2}

. The energy radiated by the filament is

0.25

times of a black body of the same area at the same temperature. Calculate the Stefan's constant.

HARD

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 25 - Thermal Radiation>NUMERICALS>Q 20

The temperature of a silver sphere of radius

5 cm is 527 ° C

. If the emissivity is

0.04

find out the energy emitted per sec from the surface of the sphere.

HARD

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 25 - Thermal Radiation>NUMERICALS>Q 21

Calculate the rate of emission in

W {cm}^{- 2}

by a surface at

227 ° C

if its emissivity is

0.6

.

HARD

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 25 - Thermal Radiation>NUMERICALS>Q 22

A metallic blackened sphere of radius of

7 cm

and mass

10 kg

heated to

227 ° C

and suspended in a box maintained at

27 ° C

. Calculate the net rate of heat loss by the sphere. What will be temperature of sphere after

5 \min

? Specific heat of the metal is

420 J {kg}^{- 1} K^{- 1}

.

MEDIUM

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 25 - Thermal Radiation>NUMERICALS>Q 23

The sun's surface radiates energy at the rate of

6.3 \times 10^{7} W m^{- 2}

. Use Stefan's law to estimate the temperature of sun's surface where Stefan's constant is

σ = 5.65 \times 10^{- 8} W m^{2} K^{- 4}

MEDIUM

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 25 - Thermal Radiation>NUMERICALS>Q 24

Experimentally the intensity of solar radiation is maximum at

4753 \overset{\circ}{A}

in the visible region. Estimate the temperature of the sun assuming it as a black body. (Wien's constant is

2.92 \times 10^{- 3} m K

)

EASY

11th ICSE

IMPORTANT

ISC Physics Class XI Part 1>Chapter 25 - Thermal Radiation>NUMERICALS>Q 25

Two stars X and Y emits maximum radiation at

4800 \overset{\circ}{A}

and

6000 \overset{\circ}{A}

. If the temperature of Y is

5800 K

then what will be the temperature of X ?