Question

A spherical mirror produces an image of magnification -1 on a screen placed at a distance of 40 cm from the mirror.
a) Write the type of the mirror.
b) Find the distance of the image from the object.
c) What is the focal length of the mirror?
d) Draw a ray diagram to show the image formation in this case

Answer 1

Answer:

The image is produced on a screen and it is diminished.

a) Mirror is concave.

b) 1/f = 1/v - 1/u

Magnification = -1 = v/u

Hence -1 = v/40

v = -40.

1/f = 1/v + 1/u

= 1/-40 + (-1/40) -- because object dis. and image distance are in the negative axis.

= -1/40 - 1/40 = -2/40 = -1/20

f = -20 cm.

Focal length = -20 cm.

RAY DIAGRAM IS AS FOLLOWS :-

Object between F and C. Image beyond C. Real, inverted, diminished.

Because we need to take a look at the range of the object distance. And compare it with twice the focal length or the radius of curvature.