Home
Class 11
PHYSICS
An electric heater emits 100W of thermal...

An electric heater emits 100W of thermal radiation. The coil has a surface area of `0.02m^(2)` . Assuming that the coil radiates like a blackbody, Find its temperature. Sigma=6.00xx10^(-s)Wm^(-2)K(-4)` .

Text Solution

Verified by Experts

Let the temperature of the coil be T. The coil will emit radiation at a rate AsigmaT^(4)` . Thus, `1000W=(0.020m^(2)xx(6.0xx10^(-s)Wm^(-2)K^(-4)xxT^(4)` . Or, `T^(4)=(1000)/(0.020xx6.00xx10^(-s))K^(4)` . `=8.033xx10^(11)K^(4)` . Or, `T=995K` .
Promotional Banner

Topper's Solved these Questions

  • HEAT TRANSFER

    HC VERMA|Exercise Short Answer|11 Videos

  • HEAT TRANSFER

    HC VERMA|Exercise Objective 1|10 Videos

  • HEAT TRANSFER

    HC VERMA|Exercise EXERCIESE|1 Videos

  • HEAT AND TEMPERATURE

    HC VERMA|Exercise Exercise|4 Videos

  • INTRODUCTION TO PHYSICS

    HC VERMA|Exercise Exercises|19 Videos

Similar Questions

Explore conceptually related problems

An electric heater ofpower 1kW emits thermal radiations the surface area of heating element of heater is 200 cm^(2) . If this heating element is treated like a black bodyfind the temperature at its surface. Assume its temperature is very much higher then its surroundings.

Calculate the saturation thermionic current if 120 W is applied to a thoriated-tungsten filament of surface area 1.0 cm^2 . Assume that the surface radiates like a blackbody. The required constants are A = 3 xx10^4 A m^(-2) -K^2 , varphi = 2.6 eV, k = 8.62 xx 10^(-5) eV kK^(-1) and sigma = 6 xx 10^(-8) W m^(-2) K^(-4)

A hot water radiator at 310 K temperature radiates thermal radiation like a black body. Its total surface area is 1.6m^(2). Find the thermal power radiated by it.

The constant A in the Richardson-Dushman equation for tungsten is 60 xx 10^(4) A m^(-2) . The work function of tungsten is 4.5 eV . A tungsten cathode having a surface area 2.0 xx 10^(-5) m^2 is heated by a 24 W electric heater. In steady state, the heat radiated by the cathode equals the energy input by the heater and the temperature becomes constant. Assuming that the cathode radiates like a blackbody, calculate the saturation current due to thermions. Take Stefan constant = 6 xx 10^(-8) W m^(-2) K^(-4) . Assume that the thermions take only a small fraction of the heat supplied.

Calculate the amount of heat radiated per second by a body of surface area 12cm^(2) kept in thermal equilibrium in a room at temperature 20^(@)C The emissivity of the surface =0.80 and sigma=6.0xx10^(-s)Wm^(-2)K^(-4) .

The radiant power of a furnace of surface area of 0.6m^(2) is 34.2KW The temperature of the furance s [sigma = 5.7 xx 10^(-8) Wm^(-2) K^(-4) .

If the sun's surface radiates heat at 6.3 xx 10^(7) Wm^(-2) . Calculate the temperature of the sun assuming it to be a black body (sigma = 5.7 xx 10^(-8)Wm^(-2)K^(-4))

Assume that the total surface area of a human body is 1-6m^(2) and that it radiates like an ideal radiator. Calculate the amount of energy radiates per second by the body if the body temperature is 37^(@)C . Stefan contant sigma is 6.0xx10^(-s)Wm^(-2)K^(-4) .

The earth receives solor radiation at a rate of 8.2Jcm^(-2)min^(-1) . Assuming that the sun radiates like a blackbody, calculate the surface of the sun. The angle subtended by the sun on the earth is 0.55(@)C and the stefan constant sigma=5.67xx10^(-s)Wm^(-2)K^(-4) .

A blackbody of surface area 1cm^(2) is placed inside an enclosure. The enclosure has a constant temperature 27(@)C and the blackbody is maintained at 327(@)C by heating it electrically. What electric power is needed to maintain the temperature? sigma=6.0xx10^(-s)Wm^(-2)K(-2) .

HC VERMA-HEAT TRANSFER-Worked Out Examples
  1. The lower surface of a slab of stone of face-area 3600cm^(2) and thick...

    Text Solution

    |

  2. An icebox made of 1.5cm thick stuyrofoam has dimensions 60cmxx60cmxx30...

    Text Solution

    |

  3. A closed cubical box is made of perfectly insulating material and the ...

    Text Solution

    |

  4. A bar of copper of length 75cm and a abr of steel of length 125cm are ...

    Text Solution

    |

  5. Two parallel plates A and B are joined together to form a compound pla...

    Text Solution

    |

  6. A room has a 4mxx4mxx10cm concrete roof (K=1.26Wm^(-1)^(@)C^(-1) . At ...

    Text Solution

    |

  7. An electric heatet is uesd in a room of total wall area 137m^(2) to ma...

    Text Solution

    |

  8. Three rods of material x and three of material y are connected as show...

    Text Solution

    |

  9. A rod CD of thermal resistance 5.0KW(-1) is joined at the middle of an...

    Text Solution

    |

  10. Two thin metallic spherical shells of radii r(1) and r(2) (r(1)lt r(2...

    Text Solution

    |

  11. On a cold winter day, the atmospheric temperature is -theta (on Celsiu...

    Text Solution

    |

  12. Figure shows a large tank of water at a constant temperature theta(0)...

    Text Solution

    |

  13. One mode of an ideal monatomic gas is kept in a rigid vessel. The vess...

    Text Solution

    |

  14. monatomic ideal gas is contained in a rigid container of volume V with...

    Text Solution

    |

  15. Conside a cubical vessel of edge a having a small hole in one of its w...

    Text Solution

    |

  16. A blackbody of surface area 1cm^(2) is placed inside an enclosure. The...

    Text Solution

    |

  17. An electric heater emits 100W of thermal radiation. The coil has a sur...

    Text Solution

    |

  18. The earth receives solor radiation at a rate of 8.2Jcm^(-2)min^(-1) . ...

    Text Solution

    |

  19. The temperature of a body falls from 40^(@)C to 36(@)C in 5 minutes wh...

    Text Solution

    |

  20. A hot fbody placed in air is cooled down according to Newton's law of ...

    Text Solution

    |