Question

(1)
A security mirror used in a big showroom has radius of curvature 5
m. If a customer is standing at a distance of 20 m from the cash
counter, find the position, nature and size of the image formed in the
security mirror.
(b) Neha visited a dentist in his clinic. She observed that the dentist was
holding an instrument fitted with a mirror. State the nature of this
mirror and reason for its use in the instrument used by dentist.
​

Answer 1

Answer:

(b). Concave lens because a concave lense increases the size of image

Answer 2

(a) The image is formed at 20/3 m in front of the mirror, and the image is small and inverted.

Given,

The radius of curvature of the mirror = 5 m.

Object distance = 20 m.

To Find,

The position, nature, and size of the image.

Solution,

Using the mirror formula

1/f = 1/v+1/u

1/5 = 1/v+1/20

1/v = 1/5-1/20

1/v = 3/20

v = 20/3 m.

Now,

m = -v/u = (20/3)/20 = -1/3.

Hence, the image is formed at 20/3 m in front of the mirror, and the image is small and inverted.

(b) The mirror used by the dentist in his clinic is a concave mirror. This mirror is used because it makes an enlarged view of a patient's teeth.

#SPJ3