Home
Class 12
PHYSICS
The image of a small electric bulb fixed...

The image of a small electric bulb fixed on the wall of a room is to be obtained on the opposite wall 3m away by means of a large convex lens. What is the maximum possible focal length of the lens required for the purpose?

A

0.75 m

B

1.33 cm

C

0.75 cm

D

1.33 m

Text Solution

Verified by Experts

The correct Answer is:
C
0.75 cm
Promotional Banner

Topper's Solved these Questions

  • RAY OPTICS AND OPTICAL INSTRUMENTS

    KUMAR PRAKASHAN|Exercise SECTION-D (MULTIPLE CHOICE QUESTIONS (MCQs))(MCQs ASKED IN COMPETITIVE EXAMS)|142 Videos

  • RAY OPTICS AND OPTICAL INSTRUMENTS

    KUMAR PRAKASHAN|Exercise SECTION-D (MULTIPLE CHOICE QUESTIONS (MCQs))(MCQs FROM .DARPAN. BASED ON TEXTBOOK)(OPTICAL INSTRUMENTS)|13 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

An object is there on a wall. Now by help of convex lens, an image of object is obtained of same size as of object on the opposite parallel wall. If the lens is at distance d from second wall, then what should be the focal length of lens ?

The ciliary muscles of eye control the curvature of the lens in the eye and hence can alter the effective focal length of the system. When the muscles are fully relaxed, the focal length is maximum. When the muscles are strained, the curvature of lens increases. That means radius of curvature decreases and focal length decreases. For a clear vision, the image must be on the retina. The image distance is therefore fixed for clear vision and it equals the distance of retina from eye lens. It is about 2.5cm for a grown up person. A perosn can theoretically have clear vision of an object situated at any large distance from the eye. The smallest distance at which a person can clearly see is related to minimum possible focal length. The ciliary muscles are most strained in this position. For an average grown up person, minimum distance of the object should be around 25cm. A person suffering from eye defects uses spectacles (eye glass). The function of lens of spectacles is to form the image of the objects within the range in which the person can see clearly. The image o the spectacle lens becomes object for the eye lens and whose image is formed on the retina. The number of spectacle lens used for th eremedy of eye defect is decided by the power fo the lens required and the number of spectacle lens is equal to the numerical value of the power of lens with sign. For example, if power of the lens required is +3D (converging lens of focal length 100//3cm ), then number of lens will be +3 . For all the calculations required, you can use the lens formula and lensmaker's formula. Assume that the eye lens is equiconvex lens. Neglect the distance between the eye lens and the spectacle lens. Q. Maximum focal length of a eye lens of a normal person is

The ciliary muscles of eye control the curvature of the lens in the eye and hence can alter the effective focal length of the system. When the muscles are fully relaxed, the focal length is maximum. When the muscles are strained, the curvature of lens increases. That means radius of curvature decreases and focal length decreases. For a clear vision, the image must be on the retina. The image distance is therefore fixed for clear vision and it equals the distance of retina from eye lens. It is about 2.5cm for a grown up person. A perosn can theoretically have clear vision of an object situated at any large distance from the eye. The smallest distance at which a person can clearly see is related to minimum possible focal length. The ciliary muscles are most strained in this position. For an average grown up person, minimum distance of the object should be around 25cm. A person suffering from eye defects uses spectacles (eye glass). The function of lens of spectacles is to form the image of the objects within the range in which the person can see clearly. The image o the spectacle lens becomes object for the eye lens and whose image is formed on the retina. The number of spectacle lens used for th eremedy of eye defect is decided by the power fo the lens required and the number of spectacle lens is equal to the numerical value of the power of lens with sign. For example, if power of the lens required is +3D (converging lens of focal length 100//3cm ), then number of lens will be +3 . For all the calculations required, you can use the lens formula and lensmaker's formula. Assume that the eye lens is equiconvex lens. Neglect the distance between the eye lens and the spectacle lens. Q. Maximum focal length of a eye lens of a normal person is

The ciliary muscles of eye control the curvature of the lens in the eye and hence can alter the effective focal length of the system. When the muscles are fully relaxed, the focal length is maximum. When the muscles are strained, the curvature of lens increases. That means radius of curvature decreases and focal length decreases. For a clear vision, the image must be on the retina. The image distance is therefore fixed for clear vision and it equals the distance of retina from eye lens. It is about 2.5cm for a grown up person. A perosn can theoretically have clear vision of an object situated at any large distance from the eye. The smallest distance at which a person can clearly see is related to minimum possible focal length. The ciliary muscles are most strained in this position. For an average grown up person, minimum distance of the object should be around 25cm. A person suffering from eye defects uses spectacles (eye glass). The function of lens of spectacles is to form the image of the objects within the range in which the person can see clearly. The image o the spectacle lens becomes object for the eye lens and whose image is formed on the retina. The number of spectacle lens used for th eremedy of eye defect is decided by the power fo the lens required and the number of spectacle lens is equal to the numerical value of the power of lens with sign. For example, if power of the lens required is +3D (converging lens of focal length 100//3cm ), then number of lens will be +3 . For all the calculations required, you can use the lens formula and lensmaker's formula. Assume that the eye lens is equiconvex lens. Neglect the distance between the eye lens and the spectacle lens. Q. Maximum focal length of a eye lens of a normal person is

Diameter of a plano-convex lens is 6 cm and thickness at the centre is 3 mm. If speed of light in material of lens is 2 xx 10^8 m/s., the focal length of the lens is ......

A convex lens is placed between an object and a screen which are at a fixed distance apart for one position of the lens. The magnification of the image obtained on the screen is m_(1) . When the lens is moved by a distance d the magnification of the image obtained on the same screen m_(2) , Find the focal length of the lens.

An image of an object obtained by a convex mirror is n times smaller than the object. If the focal length of lens is f, the object distance would be ...........

A thin equiconvex lens of glass of refractive index mu=3//2 & of focal length 0.3m in air is sealed into an opening at one end of a tank filled with water (mu=4//3) .On the opposite side of the lens ,a mirror is placed inside the tank on the tank wall perpendicular to the lens axis ,as shown in figure .the separation between the lens and the mirror is 0.8m A small object is placed outside the tank in front of the lens at a distance of 0.9 m form the lens along its axis .Find the position (relative to the lens)of the image of the object fromed by the stsyem.

(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 ?

(a) For the telescope described in Exercise 9.28 (a), what is the separation between the objective lens and the eyepiece? (b) If this telescope is used to view a 100 m tall tower 3 km away, what is the height of the image of the tower formed by the objective lens? (c) What is the height of the final image of the tower if it is formed at 25cm?

KUMAR PRAKASHAN-RAY OPTICS AND OPTICAL INSTRUMENTS-SECTION-D (MULTIPLE CHOICE QUESTIONS (MCQs))(MCQs FROM .DARPAN. BASED ON TEXTBOOK)(MCQs BASED ON TEXTUAL ILLUSTRATION AND EXERCISE)
  1. (i) If f = 0.5 m for a glass lens, what is the power of the lens? (ii)...

    Text Solution

    |

  2. A convex lens has 20 cm focal length in air. What is focal length in w...

    Text Solution

    |

  3. A small candle, 2.5 cm in size is placed at 27 cm in front of a concav...

    Text Solution

    |

  4. A 4.5 cm needle is placed 12 cm away from a convex mirror of focal len...

    Text Solution

    |

  5. A tank is filled with water to a height of 12.5 cm. The apparent depth...

    Text Solution

    |

  6. A small bulb is placed at the bottom of a tank containing water to a d...

    Text Solution

    |

  7. Double-convex lenses are to be manufactured from a glass of refractive...

    Text Solution

    |

  8. What is the focal length of a convex lens of focal length 30cm in cont...

    Text Solution

    |

  9. A small telescope has an objective lens of focal length 144cm and an e...

    Text Solution

    |

  10. (a) A giant refracting telescope at an observatory has an objective le...

    Text Solution

    |

  11. (a) A giant refracting telescope at an observatory has an objective le...

    Text Solution

    |

  12. A small pin fixed on a table top is viewed from above from a distance ...

    Text Solution

    |

  13. The image of a small electric bulb fixed on the wall of a room is to b...

    Text Solution

    |

  14. A screen is placed 90cm from an object. The image of the object on the...

    Text Solution

    |

  15. At what angle should a ray of light be incident on the face of a prism...

    Text Solution

    |

  16. A small telescope has an objective lens of focal length 140cm and an e...

    Text Solution

    |

  17. A small telescope has an objective lens of focal length 140cm and an e...

    Text Solution

    |

  18. For the telescope described in Exercise 9.3 (a), what is the separatio...

    Text Solution

    |

  19. If this telescope is used to view a 100 m tall tower 3 km away, what i...

    Text Solution

    |

  20. (a) For the telescope described in Exercise 9.28 (a), what is the sepa...

    Text Solution

    |