Home
Class 12
PHYSICS
Two lenses, one convex and the other con...

Two lenses, one convex and the other concave are kept in contact. The focal length of convex lens is 30cm and that of concave lens is 20 cm. Whaat will be the equibalent focal length of the combination? What will be the nature of the combination?

Promotional Banner

Topper's Solved these Questions

  • QUESTION PAPER 2017

    UNITED BOOK HOUSE|Exercise EXERCISE|68 Videos

  • QUESTION PAPER 2019

    UNITED BOOK HOUSE|Exercise EXAMPLE |70 Videos

Similar Questions

Explore conceptually related problems

The focal length of a lens is -50 cm. The nature and power of the lens is

The radius of curvature of a concave mirror is 30 cm. What is its focal length ?

The focal length of a concave mirror in vacum is 2 m. What will be the focal length of the concave mirror in a medium of refractive index 2.76?

The focal length of a convex lens is 7 cm. If an object be kept at 10 cm distance then the image formed-

What will be the equivalent focal length for two lenses of focal length f_1 and f_2 in contact ?

What is the difference between a convex lens and concave lens?

If in a plano-convex lens, the radius of curvature of the convex surface is 10cm and the focal length of the lens is 30cm, then what is the refractive index of the material of lens ?

A plano-convex lens (f = 20 cm) is silvered at plane surface. Now focal length will be

UNITED BOOK HOUSE-QUESTION PAPER 2018-EXAMPLE
  1. Explain total internal reflection from law of refraction.

    Text Solution

    |

  2. A ray of lilght is incident at a small angle theta on a rectangular gl...

    Text Solution

    |

  3. Two lenses, one convex and the other concave are kept in contact. The ...

    Text Solution

    |

  4. Explain the cause of dispersion of light.

    Text Solution

    |

  5. What is understood by diffraction of light? In a single slit experimen...

    Text Solution

    |

  6. An unpolarised light is incident at angle of polarisation on a reflec...

    Text Solution

    |

  7. Why are polaroids used in sunglasses?

    Text Solution

    |

  8. A Person who can see objects clearly at a distance of 10cm, required s...

    Text Solution

    |

  9. Draw the curve showing the variation of de-Brogli wavelength of a part...

    Text Solution

    |

  10. Mention the inference of Davission- Grammer experiment.

    Text Solution

    |

  11. Define stopping potential.

    Text Solution

    |

  12. When a certain metal surface is illuminated with light of frequency v,...

    Text Solution

    |

  13. Using Bohr's porstulates of atomic model, derive the expression for th...

    Text Solution

    |

  14. What is ionisation energy of atom? What is the value of it for hydroge...

    Text Solution

    |

  15. What is meant by activity of a radioactive sunstance? Write its SI uni...

    Text Solution

    |

  16. Half-life of a radioactive substance is 30 days. Number of atoms in t...

    Text Solution

    |

  17. Form AND gate using NOR gates.

    Text Solution

    |

  18. Wahat is a p-n junction diode? Draw the circuit diagram of a full wav...

    Text Solution

    |

  19. Draw the output characteristic curves of a n-p-n transistor in a C-E c...

    Text Solution

    |

  20. What is Zener dioide? Draw its voltage vs currrent characteristics in ...

    Text Solution

    |