Home
Class 12
PHYSICS
The focal length of a concave mirror is ...

The focal length of a concave mirror is 50 cm. Where an object be placed, so that its image is two times and inverted

A

55cm

B

`-75cm`

C

65cm

D

85cm

Text Solution

Verified by Experts

The correct Answer is:
B
Magnification,`m=(f)/(f-u)`
Hence, `m=-2 and f=-50cm`
`-2=(-50)/(-50-u) Rightarrow100+2u=-50`
or `u=(-150)/(2)=-75cm`
Promotional Banner

Topper's Solved these Questions

  • RAY OPTICS

    DC PANDEY ENGLISH|Exercise medical entrance special format question|23 Videos

  • NUCLEI

    DC PANDEY ENGLISH|Exercise C MADICAL ENTRANCES GALLERY|46 Videos

  • REFLECTION OF LIGHT

    DC PANDEY ENGLISH|Exercise Subjective|9 Videos

Similar Questions

Explore conceptually related problems

The focal length of a concave mirror is 50cm. Where an object be placed so that its image is two times and inverted

At what distance in front of a concave mirror of focal length 10 cm, an object be placed so that its real image of size five times that of the object is obtained?

At what distance in front of a concave mirrorof focal length 10 cm, an object be placed so that its virtual image of size five times that of the object is obtained?

At what distance from a concave mirror of focal length 25 cm should an object be placed so that the size of image is equal to the size of the object.

At what distance from a concave mirror of focal length 25 cm should an object be placed so that the size of image is equal to the size of the object. Draw a ray diagram to show this.

A glass slab of thickness 3cm and refractive index 1.5 is placed in front of a concave mirror of focal length 20cm. Where should a point object be placed if it is to image on to itself?

The focal length of a concave mirror is 30 cm.Find the position of the object in front of the mirror,so that the image is three times the size of the objects.

A diverging lens of focal length 20 cm and a converging mirror of focal length 10 cm are placed coaxially at a separation of 5 cm. Where should an object be placed so that a real image is formed at the object itself ?

A converging lens of focal length 12 cm and a diverging mirror of focal length 7.5 cm are placed 5.0 cm apart with their principal axes coinciding. Where should an object be placed so that its image falls on itself ?

A plane mirror is placed 22.5 cm in front of the concave mirror of focal length 10 cm. Find where an object a can be placed between the two mirrors, so that the first image in both the mirrors coincides.

DC PANDEY ENGLISH-RAY OPTICS-Medical entrance gallary
  1. The mirror are inclined at angle of 50^(@). The number of images forme...

    Text Solution

    |

  2. If c is the velocity of light in free space, then the time taken by li...

    Text Solution

    |

  3. A beam of light consisting of red, green, and blue colors is incident ...

    Text Solution

    |

  4. A vessel consists of two plane mirrors at right angles as shown in fig...

    Text Solution

    |

  5. For having large magnification power of a compound microsope

    Text Solution

    |

  6. A beam of light is incident on a glass slab (mu = 1.54) in a direction...

    Text Solution

    |

  7. The focal length of lens of refractive index 1.5 in air is 30 cm When ...

    Text Solution

    |

  8. The focal length of a concave mirror is 50 cm. Where an object be plac...

    Text Solution

    |

  9. The diameter of the eye ball of a normal eye is about 2.5cm. The power...

    Text Solution

    |

  10. Two thin lenses, when in contact, produce a combination of power+10 d...

    Text Solution

    |

  11. A ray of light is incident at small angle I on the surface of prism of...

    Text Solution

    |

  12. A concave mirror of focal length f(1) is placed at a distance of d fro...

    Text Solution

    |

  13. The image formed by a convex mirror of focal length 30 cm is a quarter...

    Text Solution

    |

  14. In a compound microscope, the focal length of the objective and the ey...

    Text Solution

    |

  15. A thin convex lens of refractive index 1.5cm has 20cm focal length in ...

    Text Solution

    |

  16. Assertion : The resolving power of a telescope is more if the diameter...

    Text Solution

    |

  17. On the axis of a spherical mirror of focal length f a short linear obj...

    Text Solution

    |

  18. An object is placed at a distance of 10cm form a co-axial combination ...

    Text Solution

    |

  19. White light is incident on the interface of glass and air as shown in ...

    Text Solution

    |

  20. The focal length of the objective of a terrestrial telescope is 80 cm ...

    Text Solution

    |