Physics Quiz 6

Sound travels fastest through solids. This is because molecules in a solid medium are much closer together than those in a liquid or gas, allowing sound waves to travel more quickly through it. The speed of sound: in glass is 5640 m/s, in steel is 5960 m/s, in the air is 343 m/s and in water is 1452 m/s.

Prism is used to split white light into different colours. Prisms are specially shaped so that light passing through them bends. Some colours bend more than others as they pass through the prism, so they split apart.

Superconductors are those elements whose resistance falls almost to zero at very low temperatures. Superconductivity is complete disappearance of electrical resistance in various solids when they are cooled below a characteristic temperature.

Fibre optics work on the principle of total internal reflection. Light travels down a fiber optic cable by bouncing off the walls of the cable repeatedly. Each light particle (photon) bounces down the pipe with continued internal mirror-like reflection. The light beam travels down the core of the cable.

Metals are good conductors of electricity and heat because the atoms in the metals form a matrix through which outer electrons can move freely.

Smog is a kind of air pollution. The smoke usually came from large amounts of coal burning in an area and is caused by a mixture of smoke and sulphur dioxide (SO₂).

Due to the presence of pores (narrow space) in the wick, capillary action takes place, which makes the oil rise in the wick. Capillary action is the process of a liquid flowing in a narrow space without the assistance of, or even in opposition to, any external forces like gravity.

For a body moving with non-uniform velocity and uniform acceleration, Displacement–Time graph is nonlinear. Non-uniform motion occurs when an object's velocity (either the magnitude, or the direction, or both) is variable (i.e. the object undergoes acceleration).

Potential energy is the stored energy in any object or system by virtue of its position or arrangement of parts. The energy stored in a watch spring is potential energy. When a spring is compressed, it stores energy in form of elastic potential energy.

A spherical ball made of steel when dropped in a mercury container will be on the surface of mercury because the density of mercury is higher than that of steel.