Question

An object 4cm in
size is placed 25cm in
front of a concave
mirror of focal length
15cm.At what
distance should a
screen be placed from
the mirror to obtain a
sharp image. Also fnd
the size of the image.
Draw a ray diagram
to show rhe formation
of image in this case,​

Answer 1

Answer:

Given:

The size of object = 4.0cm

Distance of the object = 25cm (-ve as it is in front of mirrors)

focal length of concave mirror = 15cm (-ve)

Distance of the image is given by-

1/v + 1/u = 1/f

1/v + (-1/25)= -1/15

1/v = (-1/15)+(1/25)

= -10+6/150

= -4/150= >v=−37.5cm

The screen should be at 37.5cm in front of the lens.

The size of the image is given by-

hi/ ho= -v/u

=>hi = -v*ho/u = -(-37.5)*4/-25

hi= -150/25=−6cm

The image will be 6cm high and it will be inverted.

The image will be formed at a distance of 37.5cm from the mirror.

It will be an inverted image.