Q.The waves used by artificial satellites for communication purposes are
(A) Microwave
(B) AM radio waves
(C) FM radio waves
(D) X-rays

In order of increasing frequency, the electromagnetic spectrum runs radio waves -> microwaves -> infrared -> visible -> ultraviolet -> X-rays -> gamma rays, so microwaves have a higher frequency than radio waves but lower frequency than infrared, visible or UV.

Radio waves: roughly a few Hz up to about 10^9 Hz (~1 GHz).

Microwaves: roughly 10^9 Hz to 3 x 10^11 Hz (1 GHz to 300 GHz), i.e. above the radio band. …

Microwaves suit radar because their short wavelength gives sharp, directional beams and good penetration through weather.

Radar needs to accurately locate the direction, distance and speed of an aircraft. Because microwaves have a short wavelength (mm–cm range) compared to ordinary radio waves, they can be formed into a narrow, highly directional beam using a comparatively small antenna/dish (diffraction spreading is small when wavelength << aperture size). This narrow beam lets radar pinpoint direction precisely, and the reflected pulse gives distance (from time delay) and speed (from Doppler shift). Microwaves also readily penetrate clou …

Radar systems use microwaves because they combine good penetration through the atmosphere with the ability to be focused into narrow beams for precise target detection. The correct option is (C).

Microwave ovens use microwaves (typically ~2.45 GHz) to heat food by agitating water molecules; microwaves and radio waves are different, though neighbouring, bands of the EM spectrum.

In the electromagnetic spectrum, radio waves and microwaves are separately classified bands — radio waves have longer wavelengths/lower frequencies (used for broadcasting/communication), while microwaves have shorter wavelengths and higher frequencies (roughly 1 mm to 1 m, or 300 MHz–300 GHz). A microwave oven generates microwaves (about 2.45 GHz) using a magnetron; these waves are absorbed by water, fat and sugar molecules in fo …

A magnetron is a vacuum-tube device that generates microwaves, used e.g. in radar and microwave ovens.

A magnetron uses a strong magnetic field together with an accelerating electric field inside a vacuum tube to make electrons execute curved paths past a set of resonant cavities, causing them to give up energy as electromagnetic radiation in the micr …

Microwaves occupy the electromagnetic spectrum roughly from 1 GHz to 300 GHz.

Microwaves are electromagnetic waves lying between radio waves and infrared radiation, with wavelengths from about 1 mm to 1 m. This corresponds to frequencies of order $10^{9}$ Hz to $10^{11}$ Hz, i.e., in the gigahertz (GHz) range. They are prod …

Microwaves (short-wavelength radio waves) are ideal for point-to-point communication because of their high frequency and ability to be focused into narrow beams with small antennas.

The electromagnetic spectrum includes radio waves, microwaves, infrared, visible, ultraviolet, X-rays and gamma rays, each suited to different applications based on wavelength/frequency.

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Radar needs a highly directional beam and precise object-location capability; microwaves' short wavelength (compared to radio waves) makes both possible.

Radar (RAdio Detection And Ranging) works by transmitting electromagnetic pulses toward a target and analysing the reflected (echoed) signal to determine the target's distance, direction and speed. For this to work well:

1. Directionality: By diffraction theory, the spreading of a wave is significant when its wavelength is comparable to the size of the aperture (antenna). Since microwaves have very small wavelengths (millimetres to centimetres), a relatively small antenna/dish can produce a narrow, well-collimated beam — essential for precisely locating a target's direction.

2. Good reflection from small objects: Objects such as aircraft, ships, or storm clouds reflect electromagnetic waves efficiently when the wavelength is comparable to or smaller than the object size. Microwaves, being short-wavelength, reflect strongly off such objects, producing a detectable echo.

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