Home
Class 12
PHYSICS
A telescope has a magnification equal to...

A telescope has a magnification equal to 5 and the length of its tube is 60 cm. The focal length of its eye piece is

A

10 cm

B

20 cm

C

30 cm

D

40 cm

Text Solution

Verified by Experts

The correct Answer is:
A, C
Magnification of telescope
`m=(f_0)/(f_e)`
`therefore 5=(f_0)/(f_e)`
`therefore f_0=5f_e`
Now tube length
`f_0+f_e`
`60=5f_e+f_e`
`therefore 60 =6f_e`
`thereforef_e=10` cm
Promotional Banner

Topper's Solved these Questions

  • RAY OPTICS AND OPTICAL INSTRUMENTS

    KUMAR PRAKASHAN|Exercise SECTION-D (MULTIPLE CHOICE QUESTIONS (MCQs))(MCQs FROM .DARPAN. BASED ON TEXTBOOK)(MCQs BASED ON TEXTUAL ILLUSTRATION AND EXERCISE)|24 Videos

  • MOVING CHARGES AND MAGNETISM

    KUMAR PRAKASHAN|Exercise SECTION D (MCQs ASKED IN COMPETITIVE EXAMS)|34 Videos

  • SAMPLE QUESTION PAPER

    KUMAR PRAKASHAN|Exercise PART-B SECTION-C|5 Videos

Similar Questions

Explore conceptually related problems

Magnification of microscope of objective of focal length 5 mm is 400. If its tube length is 20 cm, then focal length of eye-piece is ......

If the volume of a cube is 1728 cm^(3) the length of its edge is ......... cm.

If we need a magnification of 375 from a compound microscope of tube length 150 mm and an objective lens of focal length 5 cm, the focal length of the eye-piece should be close to:

If the tube length of astronomical telescope is 105 cm and magnifying power is 20 for normal setting, then the focal length of the objective is .......... cm.

In an astronomical telescope in normal adjustment a straight black line of length L is drawn on inside part of objective lens. The eye-piece forms a real image of this line. The length of this image is I. The magnification of the telescope is :

What is tube length of telescope ?

A Galilean telescope of 10 -fold magnification has the length of 45 cm when adjusted to infinity. Determine : (a) the focal lengths of the telescope's objective and ocular, (b) by what distance the ocualr should be displaced to adjust the telescope to the distance of 50 m.

When an eye is focussed on a distant object, the focal length of the eye lens is ..........

KUMAR PRAKASHAN-RAY OPTICS AND OPTICAL INSTRUMENTS-SECTION-D (MULTIPLE CHOICE QUESTIONS (MCQs))(MCQs ASKED IN COMPETITIVE EXAMS)
  1. A thin lens made of glass (refractive index = 1.5) of focal length f= ...

    Text Solution

    |

  2. If we need a magnification of 375 from a compound microscope of tube l...

    Text Solution

    |

  3. A telescope has a magnification equal to 5 and the length of its tube ...

    Text Solution

    |

  4. A plano-convex lens of radius of curvature 30 cm and refractive index ...

    Text Solution

    |

  5. If nij is reftactive index of medium i with respect to medium j n21 X ...

    Text Solution

    |

  6. Magnification of microscope of objective of focal length 5 mm is 400. ...

    Text Solution

    |

  7. Refractive index of a prism is root2. One side of prism is polished, i...

    Text Solution

    |

  8. Focal length of convex lens having refractive index 1.5 is 2 cm. If th...

    Text Solution

    |

  9. Minimum deviation of prism having refractive index mu and small angle ...

    Text Solution

    |

  10. For ...... light, focal length of convex lens is maximum.

    Text Solution

    |

  11. Point source of light is placed 4 m below water surface in the medium ...

    Text Solution

    |

  12. A lens is placed between a source of light and a wall . It forms image...

    Text Solution

    |

  13. Light passes through a glass slab of refractive index .n. and thicknes...

    Text Solution

    |

  14. An object is there on a wall. Now by help of convex lens, an image of ...

    Text Solution

    |

  15. As shown in figure, a ray of light is incident on glass cube. If it ex...

    Text Solution

    |

  16. A biconvex lens is cut in such a way that its equal two halves are (i)...

    Text Solution

    |

  17. A mixed ray of red and green colour incidents obilquely on surface of ...

    Text Solution

    |

  18. Diameter of objective of a telescope is 10 cm Its distance from two di...

    Text Solution

    |

  19. Angular resolution of telescope is of order of ...... for 10 cm object...

    Text Solution

    |

  20. A combination is formed by keeping a convex lens in contact with a con...

    Text Solution

    |