Question

an object is placed at 30 cm in front of a spherical mirror if the image formed 6cm behind the mirror calculate its focal length, is the mirror convex or concave what is the nature of the image

Answer 1

let the mirror be a concave mirror,
u = -30cm
v = -6cm
f =??
By applying mirror formula..
1/ f = 1/v +1/u
1/f = 1/(-6)+ 1/ (-30)
1/f = 1/(-6)-1/30
1/f = -6/30cm
f = -5 cm
Focal length of the spherical mirror is in negative, it means it is a concave mirror.
So, image form by the concave mirror is real, inverted and diminished.

Answer 2

Let the mirror be a concave mirror,

u = -30cm

v = -6cm

f =??

By applying mirror formula..

1/ f = 1/v +1/u

1/f = 1/(-6)+ 1/ (-30)

1/f = 1/(-6)-1/30

1/f = -6/30cm

f = -5 cm

Focal length of the spherical mirror is in negative, it means it is a concave mirror.

So, image form by the concave mirror is real, inverted and diminished.