Electromagnetic Waves: JEE Main Important Questions & PYQs

Introduction

Electromagnetic waves are one of the most basic physical phenomena, consisting of oscillating electric and magnetic fields that extend and travel through space. The waves have an extensive range of wavelengths and therefore frequencies, encompassing radio waves and microwaves, infrared, visible, ultraviolet, x-rays, and gamma-ray spectrums. As these travel at the speed of light in a vacuum, the waves do not require a medium for transmission. This makes electromagnetic waves important in this day and age in which technology is advanced enough to allow wireless communication and transmission of signals for medical imaging and in remote sensing applications. Topics regarding wavelength, frequency, and energy properties have to be digested by the students, more so by those with such competitive tests as JEE Main. This will help enhance the ability to solve problems and also help understand why certain technologies that exist today were developed.

Important Questions on Electromagnetic Waves

Q: What does the term electromagnetic spectrum convey?

Expected answer: Define the electromagnetic spectrum and parts of it (radio waves, microwaves, infrared rays, visible light, ultraviolet rays, x-rays, gamma rays).

Study Tip: Illustrate the electromagnetic spectrum as a chart and define its components according to their wavelength and frequency ranges. Look for examples supporting each type.

Q: How does an electromagnetic wave move?

Expected answer: Discuss the oscillating electric and magnetic fields that travel through space without a medium, and how this facilitates propagation.

Study Tip: Employ some simulations or animations to show how electromagnetic waves propagate in space. Try out the experiments using radio waves and visualize their propagation.

Q: What is the velocity of electromagnetic waves without any medium?

Expected answer: The answer should affirm that the speed is approximately (3 imes 10^8) m/s and its relevance to physics shall be touched on.

Study tip: Examine the consistent factors derived from this speed about the general theory of relativity (i.e. Einstein). Factors affecting this speed in communication technologies have been discussed.

Q: What is the correlation between frequency and wavelength concerning electromagnetic waves?

Expected Answer: Outline and state the inverse relation with the help of the (c = lambda u) equation. 

Study Tip: Do a few practice problems where you have to calculate the frequency and the wavelength. Draw a chart of different kinds of electromagnetic waves indicating the frequencies and wavelengths of each type.

Q: What is the importance of the Plancks constant when dealing with electromagnetic waves?

Expected Answer: Elaborate on how the Plancks constant links energy with frequency and its significance in quantum physics. 

Study Tip: Look for the phenomenon known as the photoelectric effect, which shows that light has a corpuscular aspect. Try to perform or organize experiments showing this effect. 

Q: What are the uses of microwaves?

Expected Answer: Give the following examples: cooking, radar, communication, medicine, etc. 

Study Tip: Look for information on microwave oven technology or radar technology. Consider preparing a paper on the use of microwaves in contemporary society.

Q: What is an X-ray and how does it function? What is it used for? 

Expected Answer: To explain in great detail how an X-ray penetrates the tissues and its applications in medical imaging, and security. 

Study Tip: Find out when X-rays were discovered and how they progressed in medicine. Go on and try to shadow a radiologist or x-ray clinic as well. 

Q: What does infrared radiation do in everyday life? 

Expected Answer: Give some examples like remote voice controls, heating and cooling equipment, etc.

Study Tip: Play around with infrared sensors and cameras to observe their heat detection capabilities. Research how else infrared is used, especially in security, and health. 

Q: What is the effect of ultraviolet (UV) radiation on the health of an individual?

Expected Answer: Explain why UV radiation is dangerous, and where it can be used for beneficial purposes, such as low-cost sterilizing.

Study Tip: Find information about the types of UV radiation; ameliorate UV, cause skin damage – UVB and UVC and its effect on the skin. One can do a project on ways to protect from UV exposure.

Q: What do you understand by the concept of total internal reflection and how does it apply in optical fibers? 

Expected Answer: Define the principle of total internal reflection and how it is utilized in optical fibers for the transmission of signals.

Study Tip: Build a working or computerized model to illustrate a total internal reflection. Find out what are the recent changes in fiber optics technology and their effects on the rates of data transfer and communications.

Previous Year Questions (PYQs)

JEE Main 2023

Q: Which electromagnetic wave has the least wavelength?

A: Gamma rays possess the least wavelength.

Q: Give a brief description of infrared radiation in terms of its usage.

A: The main use of infrared radiation is in thermal imaging as well as in remote controls most of the time.

JEE Main 2022

Q: Which type of electromagnetic wave is applicable in radar operation?

A: Radars employ Microwaves.

Q: In a vacuum, what is the velocity of the electromagnetic wave?

A: The wave travels in the range of (3 x 10^8) m/s.

Q: How does the energy of electromagnetic waves depend upon their frequency?

A: There is a direct proportional relationship between energy and frequency, such that energy equals (E = h u), where (h) represents the constancy of Planck and ( u) represents the frequency.

JEE Main 2021

Q: What type of electromagnetic radiation is utilized in sterilization procedures?

A: Here, the sterilization purpose is served by Ultraviolet (UV) radiation.

Q: Describe the frequency range for radio waves.

A: The frequency of radio waves ranges from approximately (3 ext{kHz}) and extends to (300 ext{GHz}).

Q: How do we call this change in the direction of light waves when it travels from one medium to another?

A: This change in direction is known as refraction.

JEE Main 2020

Q: What list of waves in the electromagnetic spectrum has the longest wave to the shortest wave?

A: Radio waves > microwaves > infrared > visible light > ultraviolet > X-ray > gamma rays.

Q: Which type of electromagnetic wave causes the greenhouse effect mostly?

A: The greenhouse effect is caused mostly by infrared radiation.

Q: For what purposes X-Rays are used most in the field of medicine?

A: X-rays are useful in imaging and diagnosing the internal body structures.

JEE Main 2019

Q: Among the following which one has the highest energy?

A: Gamma rays have the highest energy. 

Q: Determine the frequency of a wave whose wavelength is (500 ext{ nm}) in length.

A: Frequency ( u = frac{c}{lambda} = frac{3 imes 10^8 ext{ m/s}}{500 imes 10^{-9} ext{ m}} = 6 imes 10^{14} ext{ Hz}).

Q: Microwaves are used mainly for what purpose?

A: Cooking and communication are the main purposes for which microwaves are used.

JEE Main 2018

Q: What is the speed of light in a vacuum?

A: The speed of light in a vacuum is approximate (3 x 10^8 m/s).

Q: which electromagnetic wave is used in night vision devices?

A: infrared waves are used in night vision devices.

Q: What does it mean when electromagnetic wave frequency is increased?

A: Higher frequency equals Higher energy and shorter wavelength.

JEE Main 2017

Q: What is the most significant use of ultraviolet rays?

A: Ultraviolet rays are mainly used for sterilization and disinfection processes.

Q: What type of electromagnetic radiation is used when the television is broadcast?

A: Television broadcasting employs radio frequency waves.

Q: Which of the following explains how wavelength is related to frequency in the case of electromagnetic waves?

A: Wavelength and frequency are said to have an inverse relationship with one another. When wavelength increases, frequency jitter decreases and vice versa.

Conclusion

In Conclusion, for students aiming for the JEE Main examination, electromagnetic waves are one topic that they must be able to master considering that it is not only common in the syllabus but also practice. By practicing important questions and looking at the patterns of previous questions, students get to learn the subject differently. There’s a need for regular practice and revision of these concepts since it will help one learn the skills of solving problems in a better way and increase self-esteem. One should not forget that regular practice coupled with a clear understanding of the basics is what will help to cope with such and other challenges in the JEE Main and to pass the examination successfully.

FAQs

1. What do we mean by electromagnetic waves?

Electromagnetic waves are waves of electric and magnetic fields that move through space and at the velocity of light.

2. In what way is electromagnetic waves created?

They are produced by the process of acceleration of charges, like electrons, within an antenna.

3. What is wave frequency and its relationship with the electromagnetic spectrum?

The electromagnetic spectrum is an aggregate of all kinds of electromagnetic waves including radio waves microwave infrared visible ultraviolet rays X-rays and gamma rays.

4. What is so special about polarization?

Polarization cuts off undesirable light, increases the quality of signals in communication, and is employed in LCD screens and three-dimensional movies.

For more updates Follow @PlanEdu