Question

36. The size of image of an object by a mirror is reducer
to (1/3)" by a mirror having focal length 20 cm. A+
what distance has the object been placed from the
mirror? What is the nature of image and the mirror
Draw ray diagram(s) to explain your answer.​

Answer 1

Answer:

Using magnification formula,

m= −

u

v

=

3

1

⇒ v= −

3

u

From mirror formula,

v

1

+

u

1

=

f

1

From above two equations,

−u

3

+

−u

1

=

20

1

u= −80 cm

So, the object is placed at a distance of 80cmin front of the mirror.