Physics Quiz 6

The density of air becomes heavier near the surface of the earth (due to gravity) and begins to lighten as we go to higher altitudes as the air becomes rarer. Thus, atmospheric pressure decreases with increase in altitude.

A pond of water appears less deep due to refraction. A pond of water appears to be less deep than it actually is because light rays from the bottom of the pond are bent away from the normal as they pass from water into the air. This makes the pond appear shallower than it really is.

Narinder Singh Kapany (1926 – 2020) was an Indian-American physicist best known for his work on fiber optics. He is credited with inventing fiber optics, and is considered the 'Father of Fiber Optics'.

Robert Watson-Watt was a pioneer of radar technology. Although he did not invent the idea of radio detection, he was the first to prove it could work on a large scale. The world's first true radar system was invented by an American electrical engineer Albert Hoyt Taylor and an American radio engineer Leo C Young.

In a rechargeable cell, chemical energy is stored within the cell. Chemical energy is energy stored in the bonds of atoms and molecules. Batteries, biomass, petroleum, natural gas, and coal are examples of chemical energy.

Electrostatic precipitators are used for air pollution control, particularly for removing harmful particulate matter from waste gases at industrial facilities and power-generating stations.

The fundamental scientific principle in the operation of a battery is dissociation of electrolytes. In dissociation of electrolytes, the addition of a solvent or of energy in the form of heat causes molecules or crystals of the substance to break up into ions (electrically charged particles).

The spokes used in the wheel of a bicycle increase its moment of inertia due to the increase in the distribution of mass. This opposes the change in the rotary motion of the wheel. Thus spokes fitted to the cycle wheel give a steady motion.

When a body is taken from earth to moon, weight changes but mass remains same. An object's weight is dependent on its mass and how strongly gravity pulls on it. The strength of gravity depends on how far away one object is from another. That's why the same object weighs different amounts on different planets.

Hydrogen is lighter than air. When a balloon is filled with hydrogen gas the weight of the balloon is less than the weight of air displaced by the balloon.