Question

calculate the distance at which the image is formed when object is placed at a distance of 30 cms in front of concave mirror of focal length 10cms. And find the magnification​

Answer 1

Given :-

◉ Distance of object from the concave mirror, u = -30 cm

◉ Focal length of the concave mirror, f = -10cm

To Find :-

◉ Distance at which the image would be formed.

◉ Magnification

Solution :-

Using the mirror formula, we have:

⇒ 1/f = 1/v + 1/u

⇒ -(1/10) = 1/v - 1/30

⇒ 1/v = 1/30 - 1/10

⇒ 1/v = (1 - 3)/30

⇒ 1/v = -2/30

⇒ v = -15 cm

Hence, The image would be formed at about 15 cm infront of the concave mirror.

Also, We know:

⇒ m = - v/u

Where, m = Magnification

⇒ m = - ( -15/-30 )

⇒ m = - 1/2

⇒ m = -0.5

Hence, The magnification would be -0.5

Finally,

• Image distance, v = - 15 cm
• Magnification, m = -0.5

Some Information :-

☛ The focal length of concave mirror is always negative, since it is measured against the incident rays. While focal length of convex mirror is always positive because it is measured in the direction of incident rays.