### Theory:

Devices that works on the principle of multiple reflections:
Certain devices, such as periscopes, bend light and assist in viewing the image of an object that cannot be seen with the naked eye. The principle of a periscope is multiple reflections of light. Mirrors in the barbershop and kaleidoscopes also forms multiple images due to the multiple reflections of light.
 Periscope Kaleidoscope Mirrors in barbershop

Periscope:
• Periscopes are optical devices used to look at objects that are not in the observer's line of sight.
• There are two mirrors inside the periscope that are inclined at a $$45°$$ angle.
• Submarines, the military, the navy, and nuclear reactors all use periscopes.
Principle diagram of a periscope

Kaleidoscope:
• Kaleidoscope is a device that works on the principle of multiple reflections with the help of multiple mirrors.
• It is made up of a cylindrical structure with three plane mirrors inside it that contains several pieces of beads, broken glass, colourful bangles, pebbles.
• From one end, the observer can see the Kaleidoscope, and from the other end, light enters the Kaleidoscope.
• When light falls on these objects in the Kaleidoscope, multiple reflections form colourful patterns in the three Mirrors.
Kaleidoscope - Pattern

Know the difference between luminous and non-luminous objects:

 Luminous Non-luminous objects Objects that can emit light energy by themselves are known as luminous objects. Objects that cannot emit light energy by themselves are known as non-luminous objects. Example:Sun and candle Example:Moon and trees Electric bulb Tree
Reference:
https://pixabay.com/illustrations/tree-elevation-landscape-5373563/
https://www.maxpixel.net/Bulb-Electricity-Electric-Bulb-Electric-Light-Lamp-160207
https://pixabay.com/photos/kaleidoscope-energy-mandala-lsd-4979634/
https://commons.wikimedia.org/wiki/File:Kaleidoscope_tube_1.jpg