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
Refer to fig.
Let θ bet he angle between the two mirrors OM1 and OM2. The incident ray AB is parallel to mirror OM2 and strikes the mirror OM1 at an angle of incidence equal to α. It is reflected along BC; the angle of reflection being α. Form fig. We have
Similarly for reflection at mirror OM2, we have
Now in triangle OBC; 3θ = 180o. Therefore
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?
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?
An observer moves towards a stationary plane mirror at a speed of 4 ms–1. With what speed will his image move towards him?
Which mirror should be used to obtain a parallel beam of light from a small lamp?
Choose the only wrong statement from the following.
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
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
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?
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?
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