Home
Class 12
PHYSICS
If radius of curvature of curved surface...

If radius of curvature of curved surface of plano-convex lens of refractive index 1.5 is 60 cm, then its focal length is ...... cm.

A

`-60`

B

`120`

C

`60`

D

`-120`

Text Solution

Verified by Experts

The correct Answer is:
A, B
`1/f=(n-1)[(1)/(R_1)-(1)/(R_2)]`
`=(1.5-1)[(1)/(infty)-(1)/(-60)] R_1=infty,R_2=-60` cm
`=0.5xx(1)/(60)`
`therefore f=(60)/(0.5)`
= 120 cm and fis positive for convex lens.
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

The redius of curvature of the convex face of a plano-convex lens is 12cm and its refractive index is 1.5. a. Find the focal length of this lens. The plane surface of the lens is now silvered. b. At what distance form the lans will parallel rays incident on the convex face converge? c. Sketch the ray diagram to locate the image, when a point object is places on the axis 20cm from the lens. d. Calculate the image distance when the object is placed as in (c).

The radius of curvature of the curved surface of a plano-convex lens is 20 cm. If the refractive index of the material of the lens be 1.5, it will

Radius of curvature of a concave mirror is 20 cm, then its focal length is ...... cm.

One side of radius of curvature R_2=120 cm of a convexo-convex lens of material of refractive index mu=1.5 and focal length f_1=40 cm is slivered. It is placed on a horizontal surface with silvered surface in contact with it. Another convex lens of focal length f_2=20 cm is fixed coaxially d=10 cm above the first lens. A luminous point object O on the axis gives rise to an image coincide with it. Find its height above the upper lens.

The adjacent figure shows a thin plano-convex lens of refractive index mu_1 and a thin plano-concave lens of refractive index mu_2 , both having same radius of curvature R of their curved surfaces. The thin lens of refractive index mu_3 has radius of curvature R of both its surfaces. This lens is so placed in between the plano-convex and plano-concave lenses that the plane surfaces are parallel to each other. The focal length of the combination is

Focal length of thin lens of refractive index 1.5 is 15 cm. When placed on liquid of refractive index 4/3 , then its focal length will be ...... cm.

A concave or convex lens is given such that radii of curvature are same. If refractive index of glass is 1.5, then its focal length = ...... where R = radius of curvature.

(i) If f = 0.5 m for a glass lens, what is the power of the lens? (ii) The radii of curvature of the faces of a double convex lens are 10 cm and 15 cm. Its focal length is 12 cm. What is the refractive index of glass? (iii) A convex lens has 20 cm focal length in air. What is focal length in water? (Refractive index of air-water = 1.33, refractive index for air-glass = 1.5.)

(i) If f = + 0.5 m , what is the power of the lens ? (ii) The radii of curvature of the faces of a double convex lens are 9 cm and 15 cm . Its focal length is 12 cm . What is the refractive index of glass ?

KUMAR PRAKASHAN-RAY OPTICS AND OPTICAL INSTRUMENTS-SECTION-D (MULTIPLE CHOICE QUESTIONS (MCQs))(MCQs ASKED IN COMPETITIVE EXAMS)
  1. A defect of vision in which lines in one plan of an object appear in f...

    Text Solution

    |

  2. Antistokes lines is Raman Scattering are the lines of ..... frequency ...

    Text Solution

    |

  3. The time taken by the sunlight to reach the bottom of a tank of depth ...

    Text Solution

    |

  4. As shown in figure, a plano-concave lens is placed in such a way that ...

    Text Solution

    |

  5. A ray of light passes from a medium A having refractive index 1.6 to t...

    Text Solution

    |

  6. Angle of minimum deviation for a prism of refractive index 1.5 is equa...

    Text Solution

    |

  7. Power of plane mirror is ......

    Text Solution

    |

  8. Light waves travel from optically rarer medium to optically denser med...

    Text Solution

    |

  9. If the size of the particle scattering the light is smaller than the w...

    Text Solution

    |

  10. If the focal length of a lens for red and violet light rays respective...

    Text Solution

    |

  11. Time taken by the sunlight to pass through a slab of 4 cm and refracti...

    Text Solution

    |

  12. A convex lens of focal length 12.5 cm is used as a simple microscope. ...

    Text Solution

    |

  13. If wavelength of incident light for Rayleigh scattering is decreased f...

    Text Solution

    |

  14. Two thin lenses of focal lengths f1 and f2, are in contact and coaxial...

    Text Solution

    |

  15. If deviation by a prism with small prism angle with refractive index 1...

    Text Solution

    |

  16. If radius of curvature of curved surface of plano-convex lens of refra...

    Text Solution

    |

  17. Focal length of thin lens of refractive index 1.5 is 15 cm. When plac...

    Text Solution

    |

  18. If tube length of astronomical telescope is 96 cm and magnification is...

    Text Solution

    |

  19. In optical fiber the refractive index of the material of the core is……...

    Text Solution

    |

  20. If a size of particle is a and wavelength of light islambda , for a lt...

    Text Solution

    |