Question

An object 5 cm high is placed at a distance 60 cm
in front of a concave mirror of focal length 10 cm.
Find (i) the position and (ii) size, of the image.
Ans. (i) 12 cm in front of the mirror, (ii) 1 cm​

Answer 1

Answer:

Object distance , u= -60cm

Focal lenght , f =-10cm

Object size = 5 cm

v =?

Mirror formula,

1/v + 1/u = 1/f

1/v = 1/u - 1/f

1/v= 1/-(60) +1/-(10)

1/v = -1+6/60

1/v = -5/60

1/v = -1/12

v = -12

Image position = -12

Size of the image,

Magnification , m= -v/u

m = -(-12)/-60

m = 12/-60

m = 1/-5

m= -0.2

Then ,

m = h'/h

-0.2= h'/5

-0.2 × 5 = h'

h' = -1