A radio wave is a form of electromagnetic radiation. It has the longest wavelength in the entire spectrum of electromagnetic radiation. It usually has a frequency of 300 GHz and below. In 1867, radio waves were initially predicted by electromagnetism theory put forward by James Clerk Maxwell. Specifically, Maxwell’s equations showed that a coupled electric and magnetic field moves through space as electromagnetic waves. He put forward that visible light was made of electromagnetic waves of extremely short wavelengths. In 1886, Heinrich Hertz showed the practical side of Maxwell’s waves by experimentally producing radio waves in his research laboratory. He demonstrated that they showed the same wave characteristics as visible light: refraction, standing waves, polarisation, and diffraction. Just like every electromagnetic radiation, radio waves in a vacuum move at light speed and slightly less speed in the Earth’s atmosphere. They are produced by charged particles that are going through acceleration—for example, time-changing electric currents. Natural radio waves are released by astronomical objects and lightning. They are among blackbody radiation released by all hot objects.
Important Radio Waves Questions with Answers
1) What is electromagnetic radiation?
Electromagnetic radiation is made of electromagnetic fields, which travel through space or any medium and possess electromagnetic radiant energy. The spectrum of electromagnetic radiation includes light, radio waves, infrared, microwaves, gamma rays, X-rays, and ultraviolet (collectively called the electromagnetic spectrum).
2) What are the different types of electromagnetic radiation?
Electromagnetic radiations have both electric fields and magnetic fields. They are differentiated according to their frequency. The different types of electromagnetic radiation are given below.
Microwaves: These radiations are used for cooking food and transferring information. They are represented in centimetres.
Radio waves: These radiations possess the longest wavelength in the electromagnetic spectrum. They are employed to transmit data from and to satellites, radar, and radio.
Visible light: These electromagnetic waves have a wavelength ranging from 390 nm to 700 nm.
Infrared: These radiations are called the near and far infrared. One of the familiar examples of an object that emits infrared is the human body.
X-rays: These electromagnetic waves are extensively used for medical applications. For example, scanning the skeleton system.
UV radiation: Ultraviolet waves are naturally produced by the Sun.
Gamma rays: Gamma radiations possess the shortest wavelength in the EM spectrum.
3) What are radio waves?
A radio wave is a type of electromagnetic wave. It has the longest wavelength in the entire electromagnetic radiation spectrum. It generally has a frequency of about 300 GHz and below.
4) How are radio waves artificially produced?
Radio waves are produced artificially by an electronic device known as a transmitter, which is attached to an antenna that emits radio waves. They are collected by another antenna linked to a radio receiver (it processes the accumulated signals). Radio waves are extensively employed in technologies for broadcasting, radio communication, radio and radar navigation systems, wireless communication devices, communications satellites, etc.
5) What are radio telescopes?
Radio telescopes are used to observe planets, stars, comets, galaxies, and cosmic clouds. Analysing the radio waves coming from these celestial objects, astronomers learn about their location, motion, structure, and composition. Radio astronomy has a significant advantage because rain, clouds, and sunlight do not influence observations.
6) Who proved the existence of radio waves?
Heinrich Hertz showed the presence of radio waves with the help of a spark gap connected to an induction coil and an independent spark gap on the receiving antenna. When radio waves produced by the coil transmitter’s sparks were collected by the receiving antenna, the resulting sparks would go over its gap as well. He discovered in his tests that these signals had all the characteristics of EM waves.
7) Radio waves possess the longest _______ in the EM spectrum.
Answer: wavelength
Explanation: Radio waves possess the longest wavelength in the EM spectrum.
8) What are the main astronomical sources of radio waves?
Outer space is full of radio wave sources: galaxies, stars, planets, gas clouds, dust clouds, pulsars, neutron stars, and black holes. Examination of these celestial bodies allows researchers to understand the chemical composition and physical properties of these radio sources and the phenomena that produce these emissions.
9) Explain radio communication.
Radio antennae are used to accept radio signals from FM or AM stations. These antennae collect countless radio signals, and radio tuners are needed to tune targeted signals. It can all be worked out using resonators (sometimes called inductors) which are circuits with crystal oscillators and capacitors. The resonators are precisely designed to resonate at a frequency that enables the tuners that enhance sine waves at a frequency and bypass other unnecessary sine waves.
10) What is the speed of radio waves in a vacuum?
In a vacuum space, radio waves move at the speed of light “c”. When going through a physical medium, the speed slows down depending on the permittivity and permeability of the medium. The atmosphere of the Earth has thin enough air through which radio waves propagate very close to the speed of light.
11) What are the effects of radio waves on the human body?
Radio waves are non-ionising radiation. They do not possess sufficient energy to remove electrons from molecules or atoms by ionising them or breaking chemical bonds, producing chemical reactions or DNA impairments. If radio waves are absorbed by the human body in large amounts, they might generate heat. This can cause burns and tissue damage.
12) Natural ______ waves are released by astronomical objects and lightning.
Answer: radio
Explanation: Natural radio waves are released by astronomical objects and lightning.
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Practice Questions
1) What is a wave?
2) What are the differences between a longitudinal wave and a transverse wave?
3) What is meant by an electromagnetic spectrum?
4) Which is the most powerful electromagnetic radiation?
5) What is the speed of radio waves in a glass medium?
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