Question

A spherrical mirror forms an erect image three times the size of the object, If the distance between the object and the inage is 80 cm. The nature and the focal length of the mirror are
A. concave, 30 cm
B. convex, 30cm
C. concave, 15 cm
D. convex,15 cm

Answer 1

Correct Answer - A
Magnified image is formed only by concave mirror, But this image may be real or virtual

For real image,
` 2x=80cm`
`:. x=40cm`
(1)/(-120)+(1)/(-40)=(1)/(f)`
Solving, we get `f=-30 cm` .
Similarly, we can check for virtual image.