Test on Displacement Current, Electromagnetic Waves, and the
Electromagnetic Spectrum
Section 1: Multiple Choice Questions (MCQs)
1. Displacement current is associated with which of the following phenomena?
o (A) Changing electric fields in time
o (B) Changing magnetic fields in time
o (C) Static electric fields
o (D) Static magnetic fields
2. Which of the following is true for electromagnetic waves?
o (A) They require a medium to propagate.
o (B) They do not carry energy.
o (C) They can travel through a vacuum.
o (D) They are longitudinal waves.
3. Which of the following is not a characteristic of electromagnetic waves?
o (A) They are transverse waves.
o (B) They have an electric field and a magnetic field that oscillate
perpendicular to each other.
o (C) They require a medium to propagate.
o (D) They travel at the speed of light in a vacuum.
4. What is the speed of light in a vacuum?
o (A) 3 × 10⁶ m/s
o (B) 3 × 10⁸ m/s
o (C) 3 × 10⁷ m/s
o (D) 1 × 10⁸ m/s
5. Which of the following is the correct order of electromagnetic waves in
increasing wavelength?
o (A) Microwaves, infrared, visible, ultraviolet, X-rays
o (B) Radio waves, microwaves, infrared, visible, ultraviolet
o (C) X-rays, ultraviolet, visible, infrared, microwaves
o (D) Gamma rays, X-rays, ultraviolet, visible, radio waves
6. Which of the following electromagnetic waves have the shortest wavelength?
o (A) Radio waves
o (B) Microwaves
o (C) X-rays
o (D) Gamma rays
7. What is the characteristic property of electromagnetic waves?
o (A) They have both electric and magnetic components.
o (B) They travel only through a medium.
o (C) They only travel in a vacuum.
o (D) They propagate as longitudinal waves.
8. In which part of the electromagnetic spectrum does the visible light lie?
o (A) Radio waves
o (B) Microwaves
o (C) Infrared
o (D) Between ultraviolet and infrared
9. Which electromagnetic wave is commonly used for communication via satellites?
o (A) Microwaves
o (B) Radio waves
o (C) Infrared
o (D) X-rays
10. Gamma rays have the highest energy in the electromagnetic spectrum. What is
one of their uses?
o (A) Medical imaging
o (B) Cooking food
o (C) Communication
o (D) Heating water
Section 2: Fill in the Blanks
11. The concept of displacement current was introduced by ________ to explain the
continuity of current in the presence of changing electric fields.
12. Electromagnetic waves are a combination of ________ and ________ fields
oscillating perpendicular to each other.
13. The wavelength of visible light ranges from ________ nm to ________ nm.
14. The electromagnetic spectrum is ordered from long to short wavelengths as radio
waves, microwaves, infrared, visible, ultraviolet, X-rays, and ________.
15. The energy of electromagnetic waves increases as their wavelength ________.
Section 3: Short Answer Questions
16. What is displacement current and why is it important in the context of
electromagnetic waves?
17. Explain the transverse nature of electromagnetic waves.
18. Describe the characteristics of electromagnetic waves.
19. What are the uses of radio waves in communication?
20. What is the difference between X-rays and gamma rays in terms of their energy
and uses?
21. Explain the importance of the electromagnetic spectrum in various technologies.
Section 4: Numericals
22. The frequency of a radio wave is 100 MHz. What is its wavelength? (Speed of
light = 3 × 10⁸ m/s)
23. An electromagnetic wave has a wavelength of 5 × 10⁻³ m. What is its frequency?
(Speed of light = 3 × 10⁸ m/s)
24. A microwave has a frequency of 2.5 GHz. Calculate its wavelength.
25. The energy of an electromagnetic wave is directly proportional to its frequency.
If a radio wave has an energy of 2 × 10⁻¹⁹ J, what is the energy of a gamma ray
with a frequency 100 times higher?
Section 5: NCERT Questions
26. Explain the concept of displacement current and how it is related to Maxwell's
equations.
27. Describe the relationship between frequency, wavelength, and energy in
electromagnetic waves.
28. Why are electromagnetic waves considered transverse waves?
29. What are the practical applications of ultraviolet rays in daily life?
30. Explain the differences between the various regions of the electromagnetic
spectrum in terms of their wavelength, frequency, and uses.
