Home
Class 12
PHYSICS
A lens having focal length f and apertu...

A lens having focal length f and aperture of diameter d forms an image od intensity I, Aperture of diameter `d//2` in central region of lens is covered by a block paper. Focal length of lens intensity of image now will be respectively :

A

`f and 4 I/4`

B

`(3f)/4 and I/2`

C

`f and (3I)/4`

D

`f/2 and I/2`

Text Solution

Verified by Experts

Promotional Banner

Topper's Solved these Questions

  • MODEL QUESTION PAPER 6

    SARAS PUBLICATION|Exercise EXERCISE|45 Videos

Similar Questions

Explore conceptually related problems

The focal length of a concave lens with power -4D is ……………….

1D is the power of a lens whole focal length is ________.

The focal length of a converging lens are f_v and f_r for violet and red light respectively.

Calculate the focal length of a corrective lens having power + 2.5 D .

Power of a lens is -4D, then its focal length is

Ankit developed an eye defect at the age of 65 yrs and had to wear a lens of power +3D. Find the focal length of the lens

A concave lens of focal length 20 cm is placed at a distance of 35 cm from an object. Find the position of the image and its magnification.

A point source of light is placed at a distance of 2f from a converging lens of focal length f. The intensity on the other side of the lens is maximum at a distance

An object is placed at 50 cm from a lens produces a virtual image at a distance of 10 cm in front of the lens . What is the focal length of the lens ? Is it converging or diverging ?

SARAS PUBLICATION-OPTICS-EXAMPLE
  1. The number of photo-electrons emitted for light of a frequency upsilon...

    Text Solution

    |

  2. A ray of light travelling in a transparent medium of refractive index ...

    Text Solution

    |

  3. A lens having focal length f and aperture of diameter d forms an imag...

    Text Solution

    |

  4. Which of the following is not due to total internal reflection?

    Text Solution

    |

  5. A biconvex lens has a radius of curvature of magnitude 20 cm.Which one...

    Text Solution

    |

  6. Light of two different frequencies whose photons have energies 1 eV an...

    Text Solution

    |

  7. A ray of light is incident at angle of incident ,I, on one face of a p...

    Text Solution

    |

  8. A concave mirror of focal length ‘f1' is placed at a distance‘d’ from...

    Text Solution

    |

  9. A source of light is placed at a distance of 50 cm from a photo cell ...

    Text Solution

    |

  10. Two plane mirrors are inclined at 70^@. A ray incident on one mirror a...

    Text Solution

    |

  11. The reddish appearance of rising and setting sun is due to

    Text Solution

    |

  12. In Young 's double slit experiment the distance between the slits and ...

    Text Solution

    |

  13. Ratio of longest wavelength corresponding to Lyman and Baimer series i...

    Text Solution

    |

  14. A Plano-convex lens fits exactly into a plano-concave lens. Three plan...

    Text Solution

    |

  15. For a normal eye, provides a converging power of 40Dand the least conv...

    Text Solution

    |

  16. A speeding motor cyclist sees traffic jam ahead of him. He slows dow...

    Text Solution

    |

  17. Light with an energy flux of 25xx10^4 Wm^-2 falls on a perfectly refl...

    Text Solution

    |

  18. A beam of light of wavelenght 600 nm from a distant source falls on a ...

    Text Solution

    |

  19. In the young,s double -slit experiment ,the intensity of light at a po...

    Text Solution

    |

  20. If the focal lenghth of objective lens is increased then magnifying po...

    Text Solution

    |