Home
Class 11
PHYSICS
Radius of a star acting like perfect bla...

Radius of a star acting like perfect black body is R, then at what temperature the rate of radiation will be Q ?
(Where `sigma=` Stefun - Boltzman constant)

A

`(Q)/(4piR^(2)sigma)`

B

`((Q)/(4piR^(2)sigma))^(-1/2)`

C

`((4piR^(2)Q)/(sigma))^(1/4)`

D

`((Q)/(4piR^(2)sigma))^(1/4)`

Text Solution

Verified by Experts

The correct Answer is:
D
From Stefan-Boltzmann.s law,
Here, Q is taken in place of P.
`:.Q=AsigmaeT^(4)`
`:.Q=4pir^(2)sigmaT^(4)" "(because e=1)`
`:.T=((Q)/(4pir^(2)sigma))^(1/4)`
Promotional Banner

Topper's Solved these Questions

  • THERMAL PROPERTIES OF MATTER

    KUMAR PRAKASHAN|Exercise Section - F Question from Module (Sample questions for preparation of competitive exams)|18 Videos

  • THERMAL PROPERTIES OF MATTER

    KUMAR PRAKASHAN|Exercise Question Paper (Section - A) Answer following in one sentence : (Word limit of answer is 10) (Each question carries 1 mark)|6 Videos

  • THERMAL PROPERTIES OF MATTER

    KUMAR PRAKASHAN|Exercise Section - D NCERT Exemplar Solution (Long Answer Type Questions )|8 Videos

  • SYSTEMS OF PARTICLES AND ROTATIONAL MOTION

    KUMAR PRAKASHAN|Exercise SECTION-F (SECTION-D) QUESTIONS PAPER|1 Videos

  • THERMODYANMICS

    KUMAR PRAKASHAN|Exercise Question Paper|11 Videos

Similar Questions

Explore conceptually related problems

What will be the power incident normally on unit area of spherical surface which is at distance R from the outermost surface of Sun of radius r at t^(@)C ? sigma= Stefan - Boltzmann's constant

The radiation emitted per unit time by unit area of a black body at temperature T is sigmaT^(4) wehre sigma is the Stefan-Boltzmann constant. The constant sigma can also be expressed in terms of Boltmann's constant (k), Planck's constant (h) and speed of light (3) as sigma=Ak^(alpha)h^(beta)c^(gamma) where A, alpha,beta and gamma are dimensionless constants. The set (alpha,beta,gamma) is givne by

Rate of emitted radiation energy from perfect black body at 500 K is proportional to . . . .. .

A black body emits radiation at the rate P when its temperature is T. At this temperature the wavelength at which the radiation has maximum intensity is lamda_0 , If at another temperature T' the power radiated is P' and wavelength at maximum intensity is (lamda_0)/(2) then

Parallel rays of light of intensity I=912 WM^-2 are incident on a spherical black body kept in surroundings of temperature 300K. Take Stefan-Boltzmann constant sigma=5.7xx10^-8 Wm^-2K^-4 and assume that the energy exchange with the surroundings is only through radiation. The final steady state temperature of the black body is close to

Assuming the Sun to be a spherical body of radius R at a temperature of TK, evaluate the total radiant powered incident of Earth at a distance r from the sun where r_0 is the radius of the Earth and sigma is Stefan's constant.

Two stars bound together by gravity orbit othe because of their mutual attraction. Such a pair of stars is referred to as a binary star system. One type of binary system is that of a black hole and a companion star. The black hole is a star that has cullapsed on itself and is so missive that not even light rays can escape its gravitational pull therefore when describing the relative motion of a black hole and companion star, the motion of the black hole can be assumed negligible compared to that of the companion. The orbit of the companion star is either elliptical with the black hole at one of the foci or circular with the black hole at the centre. The gravitational potential energy is given by U=-GmM//r where G is the universal gravitational constant, m is the mass of the companion star, M is the mass of the black hole, and r is the distance between the centre of the companion star and the centre of the black hole. Since the gravitational force is conservative. The companion star and the centre of the black hole, since the gravitational force is conservative the companion star's total mechanical energy is a constant. Because of the periodic nature of of orbit there is a simple relation between the average kinetic energy ltKgt of the companion star Two special points along the orbit are single out by astronomers. Parigee isthe point at which the companion star is closest to the black hole, and apogee is the point at which is the farthest from the black hole. Q. Which of the following prevents the companion star from leaving its orbit and falling the black hole?

Consider a spherical shell of radius R at temperature T. The black body radiation inside it can be considered as an ideal gas of photons with internal energy per unit volume u=U/V propT^4 and pressure P=1/3(U/V) . If the shell now undergoes an adiabatic expansion the relation between T and R is :

A metallic sphere having radius 0.08 m and mass m = 10 kg is heated to a temperature of 227^(@)C and suspended inside a box whose walls ae at a temperature of 27^(@)C . The maximum rate at which its temperature will fall is:- (Take e =1 , Stefan's constant sigma = 5.8 xx 10^(-8) W//m^(-2)K^(-4) and specific heat of the metal s = 90 cal//kg//deg J = 4.2 "Joules"//"Calorie")

Radiation from a black body at the thermodynamic temperature T_(1) is measured by a small detector at distance d_(1) from it. When the temperature is increased to T_(2) and the distance to d_(2) , the power received by the detector is unchanged. What is the ratio d_(2)//d_(1) ?

KUMAR PRAKASHAN-THERMAL PROPERTIES OF MATTER-Section - E Multiple Choice Questions (MCQs)
  1. Constant temperature of ends are T(1) and T(2) (where T(1)gtT(2)) for ...

    Text Solution

    |

  2. With rate of "7 cal cm"^(-2)s^(-1), radiations are emitted from the bl...

    Text Solution

    |

  3. Radius of a star acting like perfect black body is R, then at what tem...

    Text Solution

    |

  4. A stone of 0.36 m^(2) cross -sectional area and 0.1 m thickness has it...

    Text Solution

    |

  5. How much energy will be emitted from a furnace at 3000K temperature ac...

    Text Solution

    |

  6. Two spheres of the same material have radii 1 m and 4 m and temperatur...

    Text Solution

    |

  7. The radiation emitted by a star A is 10,000 times that of the Sun. If ...

    Text Solution

    |

  8. If the temperature of the Sun were to increase from T to 2T and its ra...

    Text Solution

    |

  9. Maximum wavelength of radiation from black body at 1640 K temp. is 1.7...

    Text Solution

    |

  10. A compound slab is made up two slabs. If thermal conductivity of their...

    Text Solution

    |

  11. Suppose the Sun expands so that its radius becomes 100 times its prese...

    Text Solution

    |

  12. Three bodies of black, gray and white colour are able to sustain upto ...

    Text Solution

    |

  13. Absorbing and emitting powers of a body are 10 and 8 respectively. The...

    Text Solution

    |

  14. By heating a iron part with flame, first it becomes red, then reddish ...

    Text Solution

    |

  15. By heating a iron part with flame, first it becomes red, then reddish ...

    Text Solution

    |

  16. Certain quantity of water cools from 70^(@)C to 60^(@)C in the first 5...

    Text Solution

    |

  17. The two ends of a metal rod are maintained at temperatures 100^(@)C an...

    Text Solution

    |

  18. On observing light from three different stars P, Q and R, it was found...

    Text Solution

    |

  19. A wall consists of alternating blocks of length 'd' and coefficient of...

    Text Solution

    |

  20. The power radiated by a black body is P and it radiates maximum energy...

    Text Solution

    |