Home
Class 11
PHYSICS
A very small hole in an electric furnace...

A very small hole in an electric furnace is used for heating metals. The hole nearly acts as black body. The area of the hole is `200mm^(2)` To keep a metal at `727^(@)C` heat energy flowing throungh this hole per sec in joules is `(sigam =5.67 xx 10^(-8)Wm^(-2)K^(-4))` .

A

`22.68`

B

`2.268`

C

`1.134`

D

`11.34`

Text Solution

Verified by Experts

The correct Answer is:
D
`P =sigmaAT^(4)`
Promotional Banner

Topper's Solved these Questions

  • TRANSMISSION OF HEAT

    NARAYNA|Exercise LEVEL-III (C.W)|1 Videos

  • TRANSMISSION OF HEAT

    NARAYNA|Exercise LEVEL- (C.W)|25 Videos

  • TRANSMISSION OF HEAT

    NARAYNA|Exercise LEVEL - 2 (C.W)|1 Videos

  • THERMODYNAMICS

    NARAYNA|Exercise Exercise|187 Videos

  • UNITS AND MEASUREMENTS

    NARAYNA|Exercise STATEMENT TYPE QUESTION|23 Videos

Similar Questions

Explore conceptually related problems

The surface area of a black body is 5xx10^(-4) m^(2) and its temperature is 727^@C . Energy radiated by it per minute is (Take sigma =5.67xx10^(-8) "J m"^(-2) s^(-1) K^(-4) )

The surface of a black body is at a tempera ture 727^(@)C and its cross section is 1m^(2) Heat radi ated from this surface in one minute in Joules is (Stefan's constant =5.7 xx 10^(-8) W//m^(2)//k^(4)) .

The power of black body at temperature 200 K is 544 W .Its surface area is (sigma=5.67xx10^(-8)Wm^(-2)K^(-2))

A body which has a surface area 5.00 cm^(2) and a temperature of 727^(@)C radiated 300 j of energy each minute. What is the emissivity of body? Steafan's constant =5.67xx10^(-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))

An incandesent light bulb has a tungsten filament that is heated to a temperature 3 xx 106(3)K when an electric current passes through it If the surface area of the filament is approximately 10^(-4)m m^(2) and it has an emissivity of 0.3 the power radiated by the bulb is nearly (sigam = 5.67 xx 10^(-8) W m^(-2) K^(-4)) .

A body which has a surface area 5.0 cm^(2) and a temperature of 727^(@)C radiater 300 J energy each minute. What is its emissivity? Stefan's Boltzmann's constat is 5.76 xx 10^(-8) Wm^(-2)K^(-4) .

A cube, which may be regarded as a perfectly black body, radiates heat at the rate of 2770.2 watt when its temperature is 27^(@)C . The volume of the cube is (sigma=5.7xx10^(8)J//m^(2)" s "K^(4))

NARAYNA-TRANSMISSION OF HEAT-LEVEL - (C.W)
  1. Three rods of identical cross-sectional area and made from the same me...

    Text Solution

    |

  2. A cube of side 10cm is filled with ice of density 0.9//c.c Thickness o...

    Text Solution

    |

  3. A slab of stone area 3600 cm^(2) and thickness 10cm is exposed on the ...

    Text Solution

    |

  4. A black body is at a temperature of 2800K The energy of radiation emit...

    Text Solution

    |

  5. When the temperature of a black body increases, it is observed that th...

    Text Solution

    |

  6. For an enclosure maintained at 2000K, the maximum radiation occurs at ...

    Text Solution

    |

  7. The power radiated by a black is P and it radiates maximum energy arou...

    Text Solution

    |

  8. The rates of heat radiation from two patches of skin each of area A on...

    Text Solution

    |

  9. A spherical black body with a radius of 12cm radiates 450W power at 50...

    Text Solution

    |

  10. If the temperature of the sun were to increase form T to 2T and its ra...

    Text Solution

    |

  11. The radiation emitted by a star A is 1000 times that of the sun. If th...

    Text Solution

    |

  12. Two electric bulbs have filaments of lengths L and 2L diameters 2d and...

    Text Solution

    |

  13. If the absolute temperature of a black body is doubled the percentage ...

    Text Solution

    |

  14. A sphere and a cube of same material and same volume are heated up to ...

    Text Solution

    |

  15. A black metal foil is warmed by radiation from a small sphere at tempe...

    Text Solution

    |

  16. A very small hole in an electric furnace is used for heating metals. T...

    Text Solution

    |

  17. The surface of a black body is at a tempera ture 727^(@)C and its cros...

    Text Solution

    |

  18. A body cools down from 50^(@)C to 45^(@)C in 5 minutes and to 40^(@)C ...

    Text Solution

    |

  19. A hot body is placed in cold surroundings It's rate of cooling is 3^(@...

    Text Solution

    |

  20. A calorimeter of water equivalent 5g has water of mass 55g upto a cert...

    Text Solution

    |