Home
Class 12
PHYSICS
A person who can see things most clearly...

A person who can see things most clearly at a distance of `10 cm`. Requires spectacles to enable to him to see clearly things at a distance of `30 cm.` What should be the focal length of the spectacles ?

A

`15 cm`(Concave)

B

`15 cm` (Convex )

C

`10 cm`

D

`0`

Text Solution

Verified by Experts

The correct Answer is:
A
For lens `u=`wants to see `=-30cm`
and `v=` can see`=-10cm`
`:. (1)/(f)=(1)/(v)-(1)/(u)=(1)/(-10)-(1)/((-30))impliesf=-15cm`
Promotional Banner

Topper's Solved these Questions

  • GEOMETRICAL OPTICS

    A2Z|Exercise Problems Based On Mixed Concepts|37 Videos

  • GEOMETRICAL OPTICS

    A2Z|Exercise Section B - Assertion Reasoning|19 Videos

  • GEOMETRICAL OPTICS

    A2Z|Exercise Prism Theory And Dispersion Of Light|45 Videos

  • ELECTROMAGNETIC WAVES AND COMMUNICATION SYSTEM

    A2Z|Exercise Section D - Chapter End Test|30 Videos

  • MAGNETISM AND MATTER

    A2Z|Exercise Section D - Chapter End Test|30 Videos

Similar Questions

Explore conceptually related problems

A far-sighted man can see clearly at a distance of 1.0m . The power of the lens that would make him see clearly at a distance of 0.2m is

If a person can sees clearly at a distance of 100 cm, then find the power of leris used to see object at 40 cm.

A person can not see the objects clearly placed at a distance more than 40 cm . He is advised to use a lens of power

A person can see clearly upto 1 m. The nature and power of the lens which will enable him to see things at a distance of 3 m is

The distance of distinct vision of a person is 50 cm . He wants to read a book placed at 25 cm . What should be the focal length of the spectacles ?

A short sighted person can see objects most distinctly at a distance of 16 cm. If he wears spectacles at a distance of 1 cm from the eye, then their focal length to see distinctly at a distance of 26 cm

A short sighted person can see objects most distinctly at a distance of 16 cm . If he wears spectacles at a distance of 1 cm from the eye, what focal length should he have so as to enable him to see distinctly at a distance of 26 cm ? ( c) The person above prefers to remove his spectacles while reading a book. Explain why ? (NCERT Solved Example)

A2Z-GEOMETRICAL OPTICS-Optical Instruments
  1. A convex lens of focal length 40 cm is in contact with a concave lens ...

    Text Solution

    |

  2. Two parallel pillars are 11 km away from an observer. The minimum dist...

    Text Solution

    |

  3. A person who can see things most clearly at a distance of 10 cm. Requi...

    Text Solution

    |

  4. Far points of myopic eye is 250 cm, then the focal length of the lens ...

    Text Solution

    |

  5. A man can see clearly up to 3 metres. Prescribes a lens for his specta...

    Text Solution

    |

  6. A satisfactory photographic print is obtained when the exposure time i...

    Text Solution

    |

  7. A person uses a lens of power +3D to normalise vision. Near point of h...

    Text Solution

    |

  8. A student can distinctly see the object upto a distance 15 cm. He want...

    Text Solution

    |

  9. The exposure time of a camera lens at the (f)/(2.8) setting is (1)/(2...

    Text Solution

    |

  10. The focal lengths of the objective and eye- lens of a microscope are 1...

    Text Solution

    |

  11. The length of the compound microscope is 14 cm. The magnifying power f...

    Text Solution

    |

  12. If the focal length of objective and eye lens are 1.2 cm and 3 cm resp...

    Text Solution

    |

  13. The focal length of objective and eye lens of a microscope are 4 cm an...

    Text Solution

    |

  14. The magnifying power of a microscope with an objective of 5 mm focal l...

    Text Solution

    |

  15. If the focal length of the objective lens is increased then

    Text Solution

    |

  16. The focal length of the objective and the eye piece of a compound micr...

    Text Solution

    |

  17. The objective lens of a compound microscope produces magnification of ...

    Text Solution

    |

  18. In a compound microscope, the focal lengths of two lenses are 1.5 cm a...

    Text Solution

    |

  19. A simple telescope, consisting of an objective of focal length 60 cm a...

    Text Solution

    |

  20. The diameter of the objective of the telescope is 0.1 metre and wavel...

    Text Solution

    |