Electromagnetic Fields and Applications MCQs December 23, 2025July 15, 2024 by u930973931_answers 20 min Score: 0 Attempted: 0/20 Subscribe 1. Which law describes the relationship between electric charges and the electric field they produce? (A) Ohm’s Law (B) Coulomb’s Law (C) Ampère’s Law (D) Faraday’s Law 2. What is the SI unit of electric flux? (A) Volt (B) Tesla (C) Weber (D) Newton 3. Which electromagnetic wave has the longest wavelength? (A) X-rays (B) Microwaves (C) Radio waves (D) Gamma rays 4. According to Maxwell’s equations, what is the relationship between electric fields and changing magnetic fields? (A) ∇ ⋅ E = ρ / ε₀ (B) ∇ × E = -∂B/∂t (C) ∇ ⋅ B = 0 (D) ∇ × B = μ₀J 5. In a vacuum, what is the speed of electromagnetic waves? (A) 3 × 10⁵ m/s (B) 3 × 10⁷ m/s (C) 3 × 10⁸ m/s (D) 3 × 10¹⁰ m/s 6. What property of a material determines how much it resists the flow of electric current? (A) Conductivity (B) Permittivity (C) Resistivity (D) Susceptibility 7. Which of the following is a vector quantity in electromagnetic theory? (A) Electric potential (B) Electric flux density (C) Electric charge (D) Electric field intensity 8. What is the SI unit of magnetic flux density? (A) Weber (B) Tesla (C) Gauss (D) Henry 9. Which law states that the induced electromotive force (EMF) in any closed circuit is equal to the negative rate of change of the magnetic flux through the circuit? (A) Lenz’s Law (B) Ohm’s Law (C) Faraday’s Law (D) Gauss’s Law 10. The phenomenon where an electric current is induced due to a change in magnetic field is known as: (A) Electromagnetic interference (B) Inductance (C) Faraday’s Law (D) Ohm’s Law 11. Which type of electromagnetic wave is used in magnetic resonance imaging (MRI)? (A) X-rays (B) Gamma rays (C) Infrared radiation (D) Radio waves 12. What does the term “permittivity” describe in the context of electromagnetic fields? (A) The ability of a material to conduct electricity (B) The property of a material that determines how much electric flux can pass through it (C) The ability of a material to sustain a magnetic field (D) The property of a material that determines how much electric field can be generated in it 13. Which statement best describes the behavior of electric field lines around a positive point charge? (A) They radiate inward toward the charge. (B) They radiate outward away from the charge. (C) They form closed loops around the charge. (D) They do not exist around a point charge. 14. According to Gauss’s Law for electricity, the electric flux through a closed surface is proportional to the: (A) Electric potential at a point within the surface (B) Charge enclosed within the surface (C) Electric field strength at a point within the surface (D) Magnetic field strength at a point within the surface 15. What is the relationship between the wavelength (λ) and frequency (f) of an electromagnetic wave? (A) λ = f (B) λ = c / f (C) f = λc (D) f = cλ 16. Which law relates the circulation of a magnetic field around a closed loop to the electric current passing through the loop? (A) Faraday’s Law (B) Gauss’s Law for Magnetism (C) Ampère’s Law (D) Lenz’s Law 17. What is the term for the property of a material to be magnetized when placed in an external magnetic field and to retain some of that magnetization after the field is removed? (A) Conductivity (B) Permeability (C) Retentivity (D) Susceptibility 18. Which type of electromagnetic wave has the highest energy? (A) Radio waves (B) Ultraviolet rays (C) Infrared radiation (D) Microwaves 19. In an AC circuit, what is the phase difference between the voltage and current in a purely resistive load? (A) 0° (B) 45° (C) 90° (D) 180° 20. What phenomenon is responsible for the appearance of colors in thin films and soap bubbles? (A) Interference (B) Diffraction (C) Polarization (D) Refraction