Question

At what distance from a concave mirror of focal length 10cm should an object be placed so that its real image is formed 20 cm from the mirror with ray diagram ​

Answer 1

Answer:

Explanation:

1/f=1/u+1/v

1/10=1/u+1/20

1/u=1/10-1/20

1/u=1/20

u=20cm

Hence object must be placed at 2f to produce a real image also at 2f.