Question

an object is placed at a distance of 10cm in front of a concave mirror and its erect and magnified image is formed at a distance of 30cm from the mirror. What is the focal length of the mirror.

Answer 1

Answer:

Since the image is erect , so the magnification ratio must be positive .

m=2

also u=−10cm

so m=−

u =2

v=−10

v=20cm

So the image is virtual and 20 cm from mirror on the other side of the object