Question

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

Solution

Correct option is

 

For a spherical mirror  The value of u for the two ends of the object of length L are u1 = u – L/2 and u2 = u + L/2. Thus the axial length of the image is

                  

                         

                    

SIMILAR QUESTIONS

Q1

The polarising angle for glass is 

Q2

What is the SI unit of luminous intensity?

Q3

What are the dimensions of luminous intensity?   

Q4

What is the luminous intensity of a lamp which produces an illuminance of 12 lux at a distance of 5.0 m from it?  

Q5

To print a photograph from a negative, the time of exposure to light from a lamp placed 60  cm away is 2.5 s. What exposure time is required if the lamp is placed 1.2 m away?

Q6

A lamp placed at a distance of 50.0 cm from a screen on one side produces the same illumination as a standard 60 cd candle placed 100 cm away on the other side of the screen. What is the luminous intensity of the lamp?

 

Q7

An observer moves towards a stationary plane mirror at a speed of 4 ms–1. With what speed will his image move towards him?  

Q8

Which mirror should be used to obtain a parallel beam of light from a small lamp?

Q9

Choose the only wrong statement from the following.

Q10

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