write the proper experiment of multiple reflection (activity 16.5) ncert class 8
Answers
- Multiple reflections
Take two plane mirrors and place them such that they make an angle between them. Place an object between the mirrors. You can see several images in both the mirror. This is because the image formed by one mirror act as the object for the second mirror. This phenomenon is referred to as multiple reflections.
The number of image formed depends on the angle between the mirrors.
The number of images formed is found using the formula.
n = (360/O) -1
n = number of images
o = angle between the two mirrors
- Instrument Based on Multiple reflection
- Kaleidoscope
This instrument works on the principle of multiple reflections. It consists of three plane mirrors inclined at an angle of 60o to each other.
The arrangement is kept in a cylindrical cardboard base with a few pieces of coloured glass at one end. The mirrors form multiple images of these glass pieces, resulting in beautiful pattern when seen from the other end. On rotating the cylindrical box, the pattern change continuously as the position of glass piece shifts.
2. Periscope
It is another instrument which uses the principle of multiple reflections. This instrument also needs two plane mirrors that are placed at an angle of 45? to the vertical. In a periscope mirrors are placed at a distance from each other. The image formed by one mirror acts as the object for the other mirror. The main use of Periscope is in submarines that remain under water.