Question

Please help me to find the answers ..........................An object is placed in front of a concave mirror of focal length 20 cm . The image formed is three times the size of the object . Calculate two possible distance of the object from the mirror.​

Answer 1

Answer:

Explanation:

Mirror: Concave.

Focal length = -20cm

h'=3h

According to magnification formula,

-v/u=h'/h

-v/u=3h/h

-v/u=3

-v=3u

v= -3u

According to mirror formula,

1/f=1/v+1/u

1/-20= 1/-3u+1/u

-1/20= -1/3u+(1/u)×3/3

-1/20= -1/3u+3/3u

-1/20= (-1+3)/3u

-1/20= 2/3u

-1×3u=2×20

-3u=40

u=40/-3

u= -40/3

u= -13.33m