Question

10. An object 3 cm tall is placed 20 cm from the front
of a concave mirror with a radius of curvature of
30 cm. Where is the image formed, and how tall
is it? If the object is moved to a position 10 cm
from the front of the mirror, what will the
characteristics of the image be?​

Answer 1

Explanation:

An object 3cm high is placed at a distance of 20cm in front of a concave mirror of radius of curvature 50cm. How would you find the position and size of the image formed?

height of the object h = 3 cm

object distance u=20 cm

radius of curvature R=50 cm

focal length f= R/2 =25 cm

image distance v = ?

size of the image h’=?

mirror formula

1/u+1/v=1/f

1/v=1/f-1/u

1/v= (1/25)-(1/20)

=(4–5)/100

=-1/100

v=-100cm

magnification m= h’/h=-v/u

m=100/20=5

5=h’/3

h’=15 cm

Image is formed at a distance of 100 cm from the mirror and is real, inverted,magnified.(-ve sign indicates the real image)