Mirror Formula and Linear magnification produced by Mirror

Mirror Formula and Linear magnification produced by Mirror

Definition of Mirror Formula :

A formula which gives the relationship between image distance (v) , object distance (u) and focal length (f) of a spherical mirror is known as the mirror formula.

Mirror Formula: 1/f = 1/u + 1/v

Where f is focal length of the mirror

             u is distance of object from mirror 

             v is distance of image from mirror

Defination of Linear Magnification: 

The ratio of the height of image to the height of object is known as Linear Magnification

m = h2/h1= height of image / height of object

Linear Magnification produced by a mirror is equal to the ratio of the image distance to the object distance , with a minus sign.

Magnification m = -v/u = -Image distance / Object distance

 m = -v/u = h2/h1

  1. If the magnification has a plus sign +m then the image is virtual and Eract.
  2. If the magnification has a minus sign -m, then the image is real and inverted.
  3. Concave mirror can be less than m< 1 , equal to m= 1 or more than m>1. 
  4. Convex mirror forms images which are smaller than the object. m<1.
  5. Height of the object will always be positive.
  6. Height of virtual image will be positive.
  7. Height of real image will be negative.
  8. A plane mirror forms image which are always of the same size as the object , therefore the magnification (m) produced by a plane mirror is always 1 , m= 1



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