Question

A concave mirror of focal length 10cm is placed 40cm away from a white screen. An object is placed between the screen and the mirror in such a way that a clear, real and inverted image of the object is formed on the screen as shown in the figure.

What will be the distance between the object and the white screen?

a) 24.5 cm
b) 25.5 cm
c) 26.7 cm
d) 27.2 cm
​

Answer 1

Answer:

According to given problem, for concave mirror,

u=−15 cm and f=−10 cm

v

1

+

−15

1

=

−10

1

, i.e., v=−30 cm

i.e., concave mirror will form real, inverted, and enlarged image I

1

of object O at a distance of 30 cm from it, i.e., at a distance 40−30=10 cm from the convex mirror.

For convex mirror, the image I

1

will act as an object and so for it u=−10 cm and f=+15 cm.

v

1

+

−10

1

=

15

1

, i.e., v=+6 cm

So, final image I

2

is formed at a distance of 6 cm behind the convex mirror and is virtual as shown in figure.

solution