Question

Per square wire of side one cm is placed perpendicular to the principal axis of a concave mirror of focal length 15 cm at a distance of 20 cm

Answer 1

-15/-20+15= 3
m=3
the area enclosed= m2
= 3×3=9

Answer 2

Answer: 9 cm^2

Step-by-step explanation:

Since

f = -15cm(sign convention)

u = -20cm(sign convention)

v = ?

Using mirror formula

1/v + 1/u = 1/f

Substituting values of v,u and f

1/v - 1/20 = - 1/15

1/v = 1/20 - 1/15

= (4-3)/60

= 1/60

v = 60 cm behind the mirror.

Let h be the height of object = 1cm

Let h' be the height of image.

m = magnification

= h'/h

= -v/u

h'/h= -v/u

Substituting values of h , v , u

h'/1 = -60/-20

h' = 60/20 = 3 cm.

Therefore area enclosed by image is equal to a^2 where a is the side of a square image.

So area enclosed by image is

3^2 = 9 cm ^2

Therefore area enclosed by the image is 9 cm ^2.

Thanks