Home
Class 12
PHYSICS
What will be the equivalent focal length...

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

A

A. `f_1f_2`

B

B. `(f_1f_2)/(f_1+f_2)`

C

C. `f_1+f_2/(f_1^2+f_2^2)`

D

D. `f_1+f_2/(f_1+f_2)`

Text Solution

Verified by Experts

Promotional Banner

Topper's Solved these Questions

  • MODEL PAPER SET-10

    UNITED BOOK HOUSE|Exercise EXERCISE|53 Videos

  • MODEL PAPER SET-12

    UNITED BOOK HOUSE|Exercise EXERCISE|31 Videos

Similar Questions

Explore conceptually related problems

Derive an expression for the equivalent focal length for two thin convex lenses in contact.

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?

Define focal length of concave mirror.

Define : Optical centre and focal length of a lens.

What is the focal length and the power of a plane mirror?

A convex lens of focal length 80 cm and a concave lens of focal length 50cm are placed in contact. The resulting will be—

What is the power and focal length- of a parallel glass slab?

The power of lens is-1.5 D. Its focal length is-

UNITED BOOK HOUSE-MODEL PAPER SET-11-EXERCISE
  1. The flux at any time t is phi = 10t^2- 50t + 250 what will be the indu...

    Text Solution

    |

  2. Two transparent media A and B are adjacent to each other. Velocity of ...

    Text Solution

    |

  3. What will be the equivalent focal length for two lenses of focal lengt...

    Text Solution

    |

  4. What among the following remains same in case.of thevvaves coming,put ...

    Text Solution

    |

  5. The property of light to bend through a sharp edge of an obstracle is:

    Text Solution

    |

  6. Which wave can not be polarised—

    Text Solution

    |

  7. In which case of the following, the dual nature of light comes into ac...

    Text Solution

    |

  8. In-8000 years a radioactive element is reduced to 1/32 of its initial ...

    Text Solution

    |

  9. an alpha particle is projected If "^14N Nucleusis projected by which N...

    Text Solution

    |

  10. 1gm of any atom is converted into energy then find out the energy is ...

    Text Solution

    |

  11. An alpha particle (""^(4)He) has a mass of 4.00300 amu. A proton has a...

    Text Solution

    |

  12. What is used as moderator in nuclear reactor:

    Text Solution

    |

  13. The stopping potential any material is 1.4Volt.What will its threshold...

    Text Solution

    |

  14. What do you mean by n type semiconductor?

    Text Solution

    |

  15. What is the effect of reversed biason any p-n junction diode— explain:

    Text Solution

    |

  16. Show the logic symbol, Binary equation and truth table for an AND gate...

    Text Solution

    |

  17. Explain— Electric field lines cut the equipotential surface normally.

    Text Solution

    |

  18. Find out the capacitance of a parallel plate capacitor in air. What is...

    Text Solution

    |

  19. Two capacitors of 0.1 mu F and 0.01 mu F are connected in series combi...

    Text Solution

    |

  20. Define the components of earths magnetic field.

    Text Solution

    |