Question

Which of the following devices make use of the phenomenon of multiple reflection?

• A. Kaleidoscope
• B. Periscope
• C. Spectacles
• D. Microscope

Answer 1

Answer: (A), (B)

Periscope

Kaleidoscope and periscope works on the principle of multiple reflection.
1)Kaleidoscope : It has 3 long mirrors put together in form of an equilateral triangle. The set of mirrors is put inside a box of almost similar size. The box contains pieces of marbles at its bottom whic get reflected in the mirrors. Since the mirrors form an equilateral triangle with each of the mirror piece inclined with each other at ${60}^{\circ }$ angle, the marble pieces get reflected a lot of times and form multiple images in the mirrors.



2)Periscope:
It is a device used for viewing objects higher than our field of vision. As shown in the image, two square shaped small mirrors are placed at angle of ${45}^{\circ }$ in a cuboid box. The light comes in through the higher window falling and reflecting from the top mirror and falling on the bottom mirror. From the bottom mirror light is reflected to the observer and the observer is able to see object which is in front of top mirror window.