Question

The focal length of a concave mirror is f and the
distance of the object from the principal focus is a. The magnitude of magnification obtained will be-
(a) f+a/f
(b) f /a
(c) f + a

Answer 1

Answer:

The correct option is A fx

We know that 

magnification (m)=h′h=−vu

where 

h′=height of the imageh=height of the objectv=distance of image from mirroru=distance of object from mirror

⇒v=h′uh



u=f+x  (as shown)

Using mirror equation,

1f=1v+1u

Putting value of v in mirror equation

1f=1(h′uh)+1u

Multiplying whole equation by u

uf=hh′+1⇒h′h=fx

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Answer 2

Answer:

f+a/f is the your answer