Question

An object has size of image is 6 cm when placed before concave mirror at a distance of 25 cm. The focal length of concave mirror is 15 cm. Find the size of the object and image distance and write the nature of image.​

Answer 1

f

1

u = -15 cm

Focal length = -10 cm

∴

v

1

=

−10

1

−

(−15)

1

⇒

v

1

=

−10

1

+

15

1

=

30

−3+2

=−

30

1

⇒v=−30cm

Magnification (m)=

u

v

=

Object height

Image height

m=−

u

v

=+

−15

30

=−2

Also, Image height=−2×6=−12 cm

Therefore, a real, inverted and enlarged image of the object is formed beyond the centre of curvature.

Answer 2

An object has size of image is 6 cm when placed before concave mirror at a distance of 25 cm. The focal length of concave mirror is 15 cm. Find the size of the object and image distance and write the nature of image.