Wave Motion (Physics)

Among the given options, supersonic waves are not an example of electromagnetic waves, while 𝛾 (Gamma)-rays, X-rays and Ultraviolet rays are examples of supersonic waves, Supersonic is used for objects which travel at a speed greater than the speed of sound.

The electromagnetic spectrum consists of all the different wavelength of electromagnetic radiations such as: Radio waves > Microwave > Infrared > Visible > Ultraviolet > X-rays > Gamma rays.

Thus it is clear that the radio waves are having the maximum wavelength while the Gamma rays are having minimum wavelength.

Shorter the wavelength, greater is the frequency and energy. In reference to energy, the sequence of the energy of electromagnetic rays is as follows:

Radio waves < Microwaves < Infrared < Visible light < Ultraviolet rays < X-rays < Gamma rays.

It is clear that among the given options, the X-rays have the maximum amount of energy than others.

The correct increasing order of the given electromagnetic waves in terms of frequency is as follows :

Radio waves < Infrared rays < Visible rays < X-rays.

Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively.

Different sources define different frequency ranges as microwave; the above broad definition includes both UHF and EHF (millimeter wave) bands. Hence, option (c) is the most appropriate answer.

Crystallography is the science that examines crystals which can be found everywhere in nature, from salt to snowflakes to gemstones.

Crystallographers use the properties of the inner structure of crystals to determine the arrangement of atoms and generate knowledge which is used by chemist, physicists and other.

Crystallographers use X-ray, neutron, and electron diffraction techniques to identify the characteristics of solid materials.

Radar is an object-detection system which uses radio waves to determine the range, angle or velocity of objects. It is used to detect the location of aircraft, ships, spacecraft, motor vehicle etc.

Remote sensing is the process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance (typically from a satellite or aircraft). Remote sensing uses a part or several parts of the electromagnetic spectrum.

It records the electromagnetic energy reflected or emitted by the Earth's surface. When electromagnetic radiation hits the surface of an object, different wavelengths are either reflected or absorbed depending on the physical and chemical properties of the object.

Special cameras collect remotely sensed images, which help researchers 'sense' things about the Earth.

It is to be noted that gamma rays are part of this electromagnetic radiation and are also used in remote sensing (in spacecrafts exploring the Moon or other planets but not in typical remote sensing of Earth observation satellites as this part of radiation is absorbed by the Earth's atmosphere).

Remote sensing observation using gamma ray spectroscopy is an effective technique to determine the elemental composition of planetary surface. Gamma ray remote sensing observations find important applications in the study of the development of the planets.

Ultraviolet radiations are mainly divided into three groups: UV-A radiations: the long wave UV-A radiations having the wavelength of 320-400 nm. They strike the surface of the Earth as the part of the rays of the sun.

UV-B radiations: the medium wave UV-B radiation has the wavelength of 280-320 nm. It is mostly absorbed by the ozone layer, but some do reach the Earth's surface.

UV-C radiations-it has a wavelength of 100-280 nm. It is completely absorbed by ozone layer and atmosphere.

Therefore, on depletion of ozone in the stratosphere, the wavelength of radiation striking the surface of the Earth will be 100 nm.

1 nm = 1.0 × 10⁻⁹ m

100 nm = 100 × 10⁻⁹

= 10² × 10⁻⁹

= 10⁻⁷ m

Infrared waves are the type of electromagnetic radiations with longer wavelengths compared to those of visible light. It is used in night vision equipment when there is insufficient visible light to see.

It is used by the soldiers to find the target, intruders and hidden bombs thus making the application of force more discriminating.