Question

A concave mirror forms a real image four times the size of the object placed at a distance of 10 cm from it. What is the radius of curvature of the mirror?   

Solution

Correct option is

16 cm

 

Since the image is erect, the magnification is negative. Hence

m = – 4.

Also               u = – 10 cm

  

Substituting for u and v in the formula   

We have         f = –8 cm.   

Hence            R = 2f = –16 cm.   

The negative sign is expected since the mirror is concave.

SIMILAR QUESTIONS

Q1

A short linear object of length L lies on the axis of a spherical mirror of focal length f at a distance u from the mirror. Its image has an axial lengthL’ equal to

Q2

Two plane mirrors are placed at right angles to each other. A ray strikes one mirror at an angle of incidence θ such that it is also reflected from the second mirror. Then, the ray reflected from the second mirror will be 

Q3

Two plane mirrors are inclined to each other at an angle of 70o. A ray is incident on one mirror at an angle θ. The ray reflected from this mirror falls on the second mirror from where it is reflected parallel to the first mirror. What is the value of θ? 

Q4

One end of a strip of a plane mirror 2.5 cm in length, is fixed. The other end rests on the top of a small vertical rod. A beam of light is reflected from the mirror and forms a spot on a screen 3 m away from the mirror. If the top of the rod is moved upwards 0.1 mm, what will be the movement of the spot? 

Q5

Two plane mirrors are inclined to each other such that a ray of light incident on the first mirror and parallel to the second is reflected from the second mirror parallel to the first mirror the angle between the two mirrors is   

Q6

A man 1.8 m tall wishes to see full-length image in a plane mirror. The length of the shortest mirror in which he can see his entire image is  

Q7

An illuminated object is placed between two plane mirrors mutually perpendicular to each other how many images are formed?

Q8

A 2.0 cm tall object is placed 15 cm from a concave mirror of focal length 10 cm. How far is the image from the mirror? 

Q9

An object 1.0 cm tall is placed 8 cm in front of a concave mirror of radius of curvature 24 cm. What is the size and the nature of the image?

Q10

In Young’s double slit experiment, the 10th maximum of wavelength λ1 is at a distance y1 from its central maximum and the 5th maximum of wavelength λ2 is at a distance y2 from its central maximum. The ratio y1/y2will be