Question

The image of a candle flame placed at a distance of 30 cm from a mirror is formed on a screen placed in front of the mirror at a distance of 60 cm from its pole. What is the nature of the mirror? Find its focal length. If the height of the flame is 2.4 cm, find the height of its image. State whether the image formed is erect or inverted.

Answer 1

Answer:

Nature of mirror=concave

Focal length= -20cm

Height of image= -4.8cm

Image is inverted

Explanation:

u= -30cm, v= -60cm, h= +2.4cm

1/f=1/v+1/u=(1/-60) + (1/-30)

               =-1/20=1/f

Thus, f= -20cm

Since focal length is negative, mirror is concave.

m=-v/u=height of image/height of object

-(-60/-30)=height of image/2.4

=height of image/24/10

=[10(height of image)]/24

-2=[10(height of image)]/24

-48=10(height of image)

-48/10= -4.8cm=height of image

Since height of image is negative, image formed is inverted.

Answer 2

Answer:

Image is Real and inverted

Explanation:

u=−30cm

v=−60cm

We know, By mirror formula  

f1​= 1/v + 1/u

​Or  

f1​= 1/-60 + 1/-30

Or  

f1 =− 3/60

Or f=−20cm

Here, the mirror's focal length is negative, representing the converging nature of the mirror. Hence the given mirror is a concave mirror of focal length =20cm.