Question

A spherical mirror forms an erect image three times the size of object.If the distance between the object and the image is 80 cm, the nature and focal length of the mirror?

Answer 1

nature is virtual, erect 

Answer 2

Answer:

30 cm

Step-by-step explanation:

since,

size of the image=3 size of the object

v=3u

m=-v/u=-3u/u=3

u+v = 80

4u=80

u=20

image is erect ,

therefore u=-20

and v=60

1/u+1/v=1/f

1/f = 1/-20 + 1/60 = -2/60 = -1/30

Therefore , f = 30cm