 # Electromagnetic Waves Questions

Electromagnetic waves are transverse waves propagating through simultaneous periodic variations of magnetic and electric fields. The magnetic and electric vectors include an angle of 90° in the medium where both components act as a coupled quantity. The frequency f is the physical quantity that decides the physical characteristics of electromagnetic waves. Due to some historical significance, the wavelength λ is generally used as the characteristic nature of EM waves. The most common examples are visible light, radio waves, ultraviolet, infrared, gamma rays and X-rays.

The usual wavelength spectrum of electromagnetic waves ranges from

$$\begin{array}{l}10^{-15}m \end{array}$$
to
$$\begin{array}{l}10^{7}m \end{array}$$
. This list starts from cosmic radiation to low, medium, and high frequency alternating currents. Only a small fraction of the EM spectrum is viewable to the human eye (between 450µm and 700µm). Normally, the light is stated as the EM wave with wavelengths of 300µm and 2000µm.

Electromagnetic waves are generated by electrically charged particles that are in the state of acceleration. These waves have the ability to interact with other charged bodies and exert force on them. They carry momentum, angular momentum and energy away from their parent particle, and can transmit those quantities to other particles they interact with.

It is clear that the fundamentals of electromagnetic waves are rooted in classical electrodynamics; numerous examinations showed that the classical version of EM waves is not enough to explain all the phenomena related to them. Theoretical physicist Max Planck developed the theory that represents electromagnetic waves not only as classical waves but also as massless particles. Albert Einstein solidified this theory with the discovery of the photoelectric effect, which cannot be analysed through classical laws and methods. The massless light particle is called a photon, and its energy is directly connected to its frequency E=hf, where h is the Planck constant and f is the photon’s frequency.

Electromagnetic waves exhibit frequency reliant interactions with the surrounding particles, which make them perfect for several applications. One of the widely used EM waves is X-rays. They are employed in medical imaging, where microwaves help to heat water-containing bodies as they have the ability to react with the dipole moment of water molecules.

Everyday life is filled with the application of electromagnetic waves or radiation. Food can be cooked in a microwave oven which utilises microwave radiation to heat food. Television sets receive signals in the form of EM waves broadcasted by the stations and satellites. Aeroplanes are directed by radar signals (microwaves). Heaters use infrared waves to generate heat. The Autofocus system in digital cameras uses infrared waves to measure and calculate the exact distance of the subject from the camera. The fluorescent or incandescent lights also produce electromagnetic radiation, which lights up everything inside their illuminating fields. These are some of the everyday uses of electromagnetic waves.

## Important Electromagnetic Waves Questions with Answers

1) What are electromagnetic waves?

Electromagnetic waves are transverse waves propagating through simultaneous periodic variations of magnetic and electric fields. The magnetic and electric vectors include an angle of 90° in the medium, where both components act as a coupled quantity.

Electromagnetic waves are generated by electrically charged particles that are in the state of acceleration. These waves have the ability to interact with other charged bodies and exert force on them. They carry momentum, angular momentum and energy away from their parent particle, and can transmit those quantities to other particles they interact with.

2) What is the significance of frequency in electromagnetic waves?

The frequency f is the physical quantity that decides the physical characteristics of electromagnetic waves. The frequency of EM waves determines the energy state and strength of the wave. Depending on the frequencies, electromagnetic waves can be mainly classified into visible light, radio waves, ultraviolet, infrared, gamma rays and X-rays.

Due to some historical significance, the wavelength λ is generally considered to be the characteristic nature of EM waves.

3) Write a brief about the usual wavelength spectrum of electromagnetic waves.

The usual wavelength spectrum of electromagnetic waves ranges from

$$\begin{array}{l}10^{-15}m \end{array}$$
to
$$\begin{array}{l}10^{7}m \end{array}$$
. This list starts from cosmic radiation to low, medium, and high frequency alternating currents. Only a small fraction of the EM spectrum is viewable to the human eye (between 450µm and 700µm). Normally, the light is stated as the EM wave with wavelengths of 300µm and 2000µm.

4) What are the common examples of electromagnetic waves?

The most common examples are visible light, radio waves, ultraviolet, infrared, gamma rays and X-rays.

5) Write a brief about electromagnetic waves and quantum mechanics.

It is clear that the fundamentals of electromagnetic waves are rooted in classical electrodynamics; numerous examinations showed that the classical version of EM waves is not enough to explain all the phenomena related to them. Theoretical physicist Max Planck developed the theory that represents electromagnetic waves not only as classical waves but also as massless particles. Albert Einstein solidified this theory with the discovery of the photoelectric effect, which cannot be analysed through classical laws and methods. The massless light particle is called a photon, and its energy is directly connected to its frequency E=hf, where h is the Planck constant and f is the photon’s frequency.

6) Write a brief about the daily life applications of electromagnetic waves.

Everyday life is filled with the application of electromagnetic waves or radiation. Food can be cooked in a microwave oven which utilises microwave radiation to heat food. Television sets receive signals in the form of EM waves broadcasted by the stations and satellites. Aeroplanes are directed by radar signals (microwaves). Heaters use infrared waves to generate heat. The Autofocus system in digital cameras uses infrared waves to measure and calculate the exact distance of the subject from the camera. The fluorescent or incandescent lights also produce electromagnetic radiation, which lights up everything inside their illuminating fields. These are some of the everyday uses of electromagnetic waves.

7) What electromagnetic waves are used to examine the crystal structure of solids?

X-rays are used to examine the crystal structure of solids.

8) Electromagnetic waves are ______ waves

Explanation: Electromagnetic waves are transverse waves.

9) Which section of the electromagnetic spectrum is absorbed from sunlight by the ozone layer?

Ultraviolet rays are absorbed by the ozone layer.

10) Electromagnetic waves are generated by ________ particles that are in the state of acceleration.

Explanation: Electromagnetic waves are generated by electrically charged particles that are in the state of acceleration.

## Practice Questions

1) What is a Gamma-Ray?

2) What is an X-Ray?

3) What is the difference between infrared and ultraviolet rays?

4) How are electromagnetic waves produced?

5) Which is the strongest electromagnetic wave?

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