Question

An object 3 cm high is placed at a distance of 8 cm from a concave mirror which produces
a virtual image 4.5 cm high :
(1) What is the focal length of the mirror ?
(ii) What is the position of image ?
(ii) Draw a ray-diagram to show the formation of image.​

Answer 1

Answer:

v/u=4.5/3=1.5=v/8

v=1.5×8=12 cm

Since image is virtual, it is formed behind the mirror. So v=+12 and u=-8

Put these values in the formula

1/f=1/v+1/u =1/12-1/8=-4/(12×8)=-1/24

f=-24, v=12