Question

an object at a distance of 20 cm from a concave mirror if the focal length of the mirror is 10 cm then calculate position of image and the magnification produce​

Answer 1

Given:-

→ Distance of the object from the

mirror = 20cm

→ Focal length of the mirror = 10cm

To find:-

→ Position of the image.

→ Magnification produced.

Solution:-

By mirror formula, we know that :-

1/u + 1/v = 1/f

Where :-

• u is position of the object.

• v is position of the image.

• f is focal length of the mirror.

Also, m (magnification) :-

m = -(v/u)

_______________________________

Since the mirror is concave, thus as per Sign Convention :-

→ u = -20cm

→ f = -10cm

Firstly, let's calculate the position of the image :-

=> 1/u + 1/v = 1/f

=> 1/v = 1/f - 1/u

=> 1/v = 1/(-10) - 1/(-20)

=> 1/v = -2+1/20

=> 1/v = -1/20

=> 20 = -v

=> v = -20 cm

Now, let's calculate the magnification :-

=> m = -(v/u)

=> m = -(-20/-20)

=> m = -1

____________________________

Thus :-

• Position of the image is 20cm in front

of the mirror.

• Magnification produced is -1 .