Physics

If the distance is doubled, the force of gravity is one-fourth as strong as before.

Hertz is the SI unit of frequency.

In driving a car to cover a distance, kinetic energy is being used in performing work.

A modem – a portmanteau of “modulator-demodulator” – is a hardware device that converts data from a digital format, intended for communication directly between devices with specialized wiring, into one suitable for a transmission medium such as telephone lines or radio.

Gamma radiation, also known as gamma rays or hyphenated as gamma-rays and denoted as y, is electromagnetic radiation of high frequency and therefore high energy. Gamma rays are ionizing radiation and are thus biologically hazardous. They are classically produced by the decay from high energy states of atomic nuclei (gamma decay), but are also created by other processes. X-radiation (composed of X-rays) is a form of electromagnetic radiation. X-rays_x000D_ have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 100 eV to 100 keV. They are shorter in wavelength than UV rays and longer than gamma rays.

Isotopes are atoms of the same element that have different numbers of neutrons but the same number of protons and electrons. The difference in the number of neutrons between the various isotopes of an element means that the various isotopes have different masses.

The device which converts sound energy into electrical energy is called microphone.

Curie point, also called Curie Temperature, temperature at which certain magnetic materials undergo a sharp change in their magnetic properties.

Ozone is present in the atmosphere in small amounts, in a layer 10 to 60 kilometres above the earth (ozonosphere) and in close proximity to the ground. The ozone layer serves as protective shield against ultraviolet (UV) rays.