Physics Quiz 5

A mirage occurs because of total internal reflection by layers of air. When the ground is very hot and the air is cool, the hot ground warms a layer of air just above the ground. When the light moves through the cold air and into the layer of hot air it is refracted (bent). A layer of very warm air near the ground refracts the light from the sky nearly into a U-shaped bend.

Most metals are good conductors of heat as solid at room temperature. But mercury is the only good conductor of heat in a liquid state due to its high coefficient of expansion.

The sky appears blue when the scattering of light takes place. As there is no atmosphere in space and hence light does not scatter into its constituent colours that is why the sky appears dark instead of blue to an astronaut in space.

The loss of water in the form of water droplets is called guttation. Guttation is the exudation of drops of xylem sap on the tips or edges of leaves of some vascular plants, such as grasses, and a number of fungi.

Aperture refers to the opening of a lens's diaphragm through which light passes. It controls the brightness of the image that passes through the lens and falls on the image sensor. The camera sensor size is one of the key elements that affect the sharpness of an image.

The sky appears blue to the human eye as the short waves of blue light are scattered more than the other colours in the spectrum, making the blue light more visible.

All magnetic objects produce invisible lines of force that extend between the poles of the object. Earth is similar to a giant bar magnet with magnetic field lines radiating from the south to the north magnetic pole.

Alnico is a family of iron alloys which in addition to iron are composed primarily of aluminium (Al), nickel (Ni), and cobalt (Co), hence the acronym al-ni-co. They also include copper, and sometimes titanium. Alnico alloys are ferromagnetic, and are used to make permanent magnets.

Asteroids are rocky objects revolving around the sun that are too small to be called planets. The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Mars and Jupiter.

The energy crisis is a result of many different strains on our natural resources. There is a strain on fossil fuels such as oil, gas, and coal due to overconsumption – which then, in turn, can put a strain on our water and oxygen resources by causing pollution.