Home
Class 12
PHYSICS
A photocell is illuminated by a small br...

A photocell is illuminated by a small bright source placed 1 m away .when the same source of light is placed 0.5 m away,the number of electrons emitted by photocathode would

A

decrease by a factor of 4.

B

increase by a factor of 4

C

decrease by a factor of 2

D

incease by factor of 2.

Text Solution

Verified by Experts

Promotional Banner

Topper's Solved these Questions

  • UNIT TEST -07

    MODERN PUBLICATION|Exercise EXERCISE|154 Videos

  • UNIT TEST -06

    MODERN PUBLICATION|Exercise EXERCISE|461 Videos

  • UNIT TEST-05

    MODERN PUBLICATION|Exercise EXERCISE|69 Videos

Similar Questions

Explore conceptually related problems

A double slit is illumnated by light of wavelengths 6000 oversetcircA . The slits are 0.1 cm apart and screen is placed 1.5 m. away. Calculate the angular position of 9th maximum in radian.

A double slit is illuminated by light of wavelength 6,000 overset @A .The slits are 0.1 cm apart and the screen is placed on meter away. Calculate the angular position of the 10th maximum in radian.

A double slit is illuminated by light of wavelength 6,000 overset @A .The slits are 0.1 cm apart and the screen is placed on metre away.Calculate separation of the two adjacent imnima.

In a Young's double slit experiment,the slits are 1.5 mm apart.When the slits are illuminated by a monochromatic source and the screen is kept 1 m aprat from the slits,width of 10 fringes is measured as 3.93 mm.Calculate the wavelength of light used.What will be the width of 10 figes,when the distance between the slits and the screen is increased by 0.5 m?The source of light used remains the same.

In a photoelectric effect set up, a point source of light of power 3.2 xx10^(-3) W emits monoenergetic photons of energy 5eV.The source is located at a distance of a stationary metallic sphere of work function 3eV and radius 8xx10^(-3)m .The efficiency of photoelectron emission is one for every 10^(6) incident photons.Assume that the sphere is isolated and initially neutral and the photoelectrons are initially swept away after emission. Calculate the number of photoelectrons emitted per second.

In a double-slit experiment the angular width of a fringe is found to be 0.2^@ on a screen placed 1 m away. The wavelength of light used is 600 nm. What will be the angular width of the fringe if the entire apparatus is immersed in water? Take refractive indexof water to be 4/3 .

Refractive index of water is 5//3 . A light source is placed in water at a depth of 4m. Then what must be the minimum radius of disc placed on water surface so that the light of source can be stopped?

MODERN PUBLICATION-UNIT TEST -07-EXERCISE
  1. Work function of a metl surface is 4.2 eV. The maximum wavelength whic...

    Text Solution

    |

  2. Sodium and copper have work functions 2.3 eV and 4.5 eV, respectively....

    Text Solution

    |

  3. A photocell is illuminated by a small bright source placed 1 m away .w...

    Text Solution

    |

  4. According to Einstein's photoelectric equation, the graph between kine...

    Text Solution

    |

  5. The surface of a metal is illuminted with the light of 400 nm.the kine...

    Text Solution

    |

  6. The threshold freuency for a metallic surface corresponds to an energy...

    Text Solution

    |

  7. This question has statement - 1 and statement - 2 of the four choice g...

    Text Solution

    |

  8. Two identical photocathodes receive the light of frequencies f1 and f2...

    Text Solution

    |

  9. The anode vollage of a photocell is kept fixed . The wavelength lambda...

    Text Solution

    |

  10. The de-Broglie wavelength of a tennis ball of mass 60 g moving wiht a ...

    Text Solution

    |

  11. If the kinetic energy of a free electron doubles,its de-Broglie wavele...

    Text Solution

    |

  12. A radiation of energy E falls normally on a perfecly reflecting surfac...

    Text Solution

    |

  13. Direction:Answer the MCQ no.15 to 17 on the basis of the folowing para...

    Text Solution

    |

  14. Wave property of electron implies that they will show diffraction effe...

    Text Solution

    |

  15. Wave property of electron implies that they will show diffraction effe...

    Text Solution

    |

  16. Wavelength of the radiation of freuquency 100 Hz is :

    Text Solution

    |

  17. Planck's constant has the dimetnsion of

    Text Solution

    |

  18. The value of Planck's constant is

    Text Solution

    |

  19. The energy of a photon of wavelelngth lambda is

    Text Solution

    |

  20. If a phtoton has velocity c and frequency v ,then wchich of the follow...

    Text Solution

    |