Practice MCQ Questions and answers on Physics-GK

Simple machine make work easier and work input > work output.

Any of the basic mechanical devices for applying a force are called simple machines.
There are 6 basic simple machines; the lever, the wheel and axle, the inclined plane, the wedge, the pulley, and the screw. Several of these simple machines are related to each other. But, each has a specific purpose in the world of doing work. A pair of scissors is not a simple machine.

The plastic material commonly used for making gear wheels is nylons.

The apparent depth will look less that its real depth due to the refraction of light. Refraction is the bending of a wave when it enters a medium where it’s speed is different. The refraction of light when it passes from a fast medium to a slow medium bends the light ray toward the normal to the boundary between the two media. The amount of bending depends on the indices of refraction of the two media and is described quantitatively by Snell’s Law.

When light passes from one medium to another, this phenomenon of change in its direction is called refraction.

The optical fibre is a device which works on the principle of total internal reflection by which light signals can be transmitted from one place to another with a negligible loss of energy.

Violet colour of light deviates the maximum during dispersion of white light by the prism as it has least wavelength among all the colours.

Diamond sparkles because of the total internal reflection that takes place in it, followed by the trapping of the light rays in it. Total internal reflection only takes place when light travels from a denser to a rarer medium.

Stars appear twinkling because of scattering of light.

The twinkling of a star is due to atmospheric refraction of starlight.