Question

The Concave mirror with a focal length 10cm and an
object of 4cm height is placed at a distance of 25cm
before mirror on principes axis find the image
distance and nature a image​

Answer 1

Answer:

hi = Size of image is 2.6 cm

v = Image  distance is 16.6 cm

Explanation:

Focal length = f = - 10 cm  

Object distance in front of a concave mirror = u = -25 cm

image distance = v = ?

hi = ?

ho =  4 cm  

 

Mirror formula,

1/f = 1/u + 1/v

=>   1/-10 = 1/-25  + 1/v

=>   1/-10 + 1/25 = 1/v

=>   25-10/-250 = 1/v

=>   v = -16.6 cm

 

m = -v/u = hi / ho

=>   m = -(- 16.6 ) / - 25 = hi/4

=>   hi = - 66.4 / 25

=>   hi = - 2.6  cm

∴ To get image of object sharp it has to be placed at v = 16.6 cm  and the size of image is 2.6 cm.

As the height of object is more and negative, nature of image is real, inverted and magnified.