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Light and Reflection -

Magnification Chart For Mirrors

**Q: What is Magnification?**

Answer: The ratio of height of image to the height of an object is known as magnification of an image and is denoted as

*m*.

Image height h' -v m = -------------------- = ---- = ---- Object height h u

The +ve value of magnification represents virtual image of an object.

The -ve value of magnification represents real image of an object.

**Q: Using magnification formula, prove that image formed by a plane mirror is at the same distance as object but behind the mirror. It is given that in plane mirror, object height and image height are equal.**

Answer: In plane mirror h' = h

h' -v m = --- = 1 = --- h u ⇒ v = -u

∴ image formed by a plane mirror is at the same distance as object but behind the mirror.

*Magnification and Type of Image and Mirror*

Magnification(m) | Type of image and its size | Type of Mirror |
---|---|---|

+1 | Virtual erect and of same size as an object | Plane |

-1 | Real inverted and of same size as an object. | Concave |

>1 and -ve | Real inverted and magnified | Concave |

< 1 and -ve | Real inverted and diminished | Concave |

> 1 and positive | Virtual, erect and magnified | Concave |

< and positive | Virtual, erect and diminished | Convex |

**Q: The magnification of a mirror is -2. Height of the object is 15cm. What is the height of the image? What type of image will it be?**

Answer: Given m = -2, h = 15cm, h' = ?

h' = m ✕ h = -2 ✕ 15cm = -30cm

It forms real inverted and enlarged image.

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