All Exams Test series for 1 year @ ₹349 only
Question

Shown in the figure are two plane mirrors XY and YZ (XY ⊥ YZ) joined at their edge. Also shown is a light ray falling on one of the mirrors and reflected back parallel to its original path as a result of this arrangement. The two mirrors are now rotated by an angle θ to their new position X'YZ', as shown. As a result the new reflected ray is at an angle α from the original reflected ray. Then :

This question was previously asked in
NDA I 2023 GAT Previous Year Paper (16-Apr-2023)
The correct answer is

α = 0

Explanation:

  • When two plane mirrors placed at 90° to each other then, the incident ray and the reflected ray are antiparallel to each other.
  • Angle between the incident ray and reflected ray is 180° 
  • As shown in the figure are two plane mirrors XY and YZ (XY ⊥ YZ) joined at their edge.
  • Also shown is a light ray falling on one of the mirrors and reflected back parallel to its original path as a result of this arrangement.
  • The two mirrors are now rotated by an angle θ to their new position X'YZ', as shown.
  • As a result, the new reflected ray is at an angle α from the original reflected ray.
  • Then α = 0°, because, after rotation of the mirror combination, reflected rays are parallel to the incident rays,
  • So, the new reflected ray is parallel to the original reflected ray.

  Additional Information

  • When two plane mirrors are placed at an angle other than 90 degrees to each other, the incident ray and reflected ray are no longer antiparallel, and their relationship is determined by the angles of incidence and reflection for each mirror.
  • The angles formed by the reflected rays can be different from each other and will depend on the angle between the mirrors.
Was this answer helpful?

Similar Questions

  1. Two identical spring balances S1 and S2 are connected one after the other and are held vertically as shown in the figure. A mass of 10 kg is hanging from S2. If the readings on S1 and S2 are W1 and W2 respectively, then :

  2. Two identical containers X and Y are connected at the bottom by a thin tube of negligible volume. The tube has a valve in it, as shown in the figure. Initially container X has a liquid filled up to height h in it and container Y is empty. When the valve is opened, both containers have equal amount of liquid in equilibrium. If the initial (before the valve is opened) potential energy of the liquid is P1 and the final potential energy is P2 then :

  3. A mass is attached to a spring that hangs vertically. The extension produced in the spring is 6 cm on Earth. The acceleration due to gravity on the surface of the Moon is one-sixth of its value on the surface of the Earth. The extension of the spring on the Moon would be:

  4. A stone is thrown horizontally from the top of a 20 m high building with a speed of 12 m/s. It hits the ground at a distance R from the building. Taking g = 10 m/s2 and neglecting air resistance will give :

  5. Consider the following statements:

    1. Distance between the longitudes becomes zero on North Pole and South Pole.

    2. Distance between the longitudes is maximum on the Equator.

    3. Number of longitudes is more than number of latitudes.

    Which of the statements given above is/are correct?

  6. A sphere of volume V is made of a material with lower density than water. While on Earth, it floats on water with its volume f1V (f1 < 1) submerged. On the other hand, on a spaceship accelerating with acceleration a < g (g is the acceleration due to gravity on Earth) in outer space, its submerged volume in water is f2V. Then:

  7. A railway wagon (open at the top) of mass M1 is moving with speed v1 along a straight track. As a result of rain, after some time it gets partially filled with water so that the mass of the wagon becomes M2 and speed becomes v2. Taking the rain to be falling vertically and the water stationery inside the wagon, the relation between the two speeds v1 and v2 is :

  8. One block of 2⋅0 kg mass is placed on top of another block of 3⋅0 kg mass. The coefficient of static friction between the two blocks is 0⋅2. The bottom block is pulled with a horizontal force F such that both the blocks move together without slipping. Taking acceleration due to gravity as 10 m/s2, the maximum value of the frictional force is :


Important Questions from Miscellaneous

  1. The magazine in which Mahatma Gandhi mentioned what he wanted the Constitution to do is:

  2. Which gas shields the surface of the earth from ultraviolet radiation from the sun?

  3. Which event is marked as an Intangible Cultural Heritage of Humanity by UNESCO?

  4. Who has been conferred with the rank of the Commander of the Order of the British Empire in 2018?

  5. Who directead the film ‘Bhuvan Shome’?

Need Expert Advice?
Test Series
NDA img
Defence
NDA 2026 Mock Test Series (Latest Pattern)
503 Tests 1 Tests Free
1066 Attempts
4.6(137)
English, Hindi

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App