Home
Class 12
PHYSICS
A biconvex lens of focal length f forms ...

A biconvex lens of focal length f forms a circular image of radius r of sun is focal plane. Then, which option is correct?

A

`pir^(2)propf`

B

`pir^(2)propf^(2)`

C

If lower half part is covered by black sheet, then area of the image is equal to `pir^(2)//2`

D

if `f` is doubled, intensitywill increase

Text Solution

Verified by Experts

The correct Answer is:
B
`r=f tanalpha`

Hence, `pir^(2)propf^(2)`
Promotional Banner

Topper's Solved these Questions

  • GEOMATRICAL OPTICS

    RESONANCE ENGLISH|Exercise Advance level Problems|35 Videos

  • GEOMATRICAL OPTICS

    RESONANCE ENGLISH|Exercise Exercise-2|62 Videos

  • EXPERIMENTAL PHYSICS

    RESONANCE ENGLISH|Exercise PART -II|10 Videos

  • GRAVITATION

    RESONANCE ENGLISH|Exercise HIGH LEVEL PROBLEMS|16 Videos

Similar Questions

Explore conceptually related problems

Rays of light from Sunn falls on a biconvex lens of focal length f an the circular image of Sun of radius r is formed on the focal plane of the lens. Then,

A convex lens of focal length f forms an image which is 1/3 times the size of the object. Then, the distance of object from the lens is

A convex lens of focal length f produces an image 1/n times than that of the size of the object. The distance of the object from the lens is:

The image of an object, formed by a combination of a convex lens (of focal length f) and a convex mirror (of radius of curvature R), set up as shown is observed to coincide with the object. Redraw this diagram to mark on it the position of the centre of the mirror. Obtain the expression for R in terms of the distances, marked as a and d, and the focal lenght f, of the convex lens.

A concave lens is placed in contact with a convex lens of focal length 25 cm . The combination produces a real image at a distance of 80 cm , when an object is at a distance of 40 cm . What is the focal length of concave lens ?

If a equiconvex lens of focal length f is cut into two halves by a plane perpendicular to the principal axis, then

A convex lens of focal length 30 cm forms an image of height 2 cm for an object situated at infinity. If a concave lens of focal length 20 cm is placed coaxially at a distance of 26 cm from convex lens then size of image would be

A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination is

A biconvex lens has focal length (2)/(3) times the radius of curvature of either surface. Calculate refraction index f material of the lens.

A biconvex lens has focal length (2)/(3) times the radius of curvature of either surface. Calculate refraction index f material of the lens.

RESONANCE ENGLISH-GEOMATRICAL OPTICS -Exercise-3
  1. A point object is placed at a distance of 20 cm from a thin plano-conc...

    Text Solution

    |

  2. The graph between object distance u and image distance v for a lens is...

    Text Solution

    |

  3. A biconvex lens of focal length f forms a circular image of radius r o...

    Text Solution

    |

  4. A ray of light travelling in water is incident on its surface open to ...

    Text Solution

    |

  5. STATEMENT-1 The formula connecting u,v and f for a spherical mirrors w...

    Text Solution

    |

  6. Two beam of red and violet color are made to pass separately through a...

    Text Solution

    |

  7. A light beam is traveling from Region I to region IV (refer figure). T...

    Text Solution

    |

  8. A ball is dropped from a height of 20m above the surface of water in a...

    Text Solution

    |

  9. A student performed the experiment of determination of focal length of...

    Text Solution

    |

  10. A ray OP of monochromatice light is incident on the face AB of prism ...

    Text Solution

    |

  11. The focal length of a thin biconvex lens is 20cm. When an object is mo...

    Text Solution

    |

  12. A biconvex lens of focal length 15cm is in front of a plane mirror. Th...

    Text Solution

    |

  13. Image of an object approaching a convex mirror of radius of curvature ...

    Text Solution

    |

  14. A large glass slab (mu=5//3) of thickness 8cm is placed over a point s...

    Text Solution

    |

  15. A light ray traveling in glass medium is incident on glass-air interfa...

    Text Solution

    |

  16. Water (with refractive index =4//3) in a tank is 18cm deep. Oil of ref...

    Text Solution

    |

  17. A bi-convex lens is formed with two thin plano-convex lenses as shown ...

    Text Solution

    |

  18. Most material have the refractive index, n gt 1. So, when a light ray ...

    Text Solution

    |

  19. Most material have the refractive index, n gt 1. So, when a light ray ...

    Text Solution

    |

  20. The image of an object, formed by a plano-convex lens at a distance of...

    Text Solution

    |