Question

A convex mirror of focal length 20 cm is placed at infinity. Find the position of the image mathematically *Wrong answers or useless answers will be reported*

Answer 1

Explanation:

Since rays are coming from infinity

For first image

u + v1 = 1

f=20cu>2f therefore infinity

v1 = 201

v=20cm

for second mirror is placed it can be

u1 +v1 = f1

u=−30cm= infinity since greater than 2f

f=−10cm

therefore

v1 =1−101+ 301

v=−15cm

again applying the lens formula for the lenses

v1 − u1 = f1

u=−35cm

f=20cm

v=46.6cm to the left of the lens.