Electromagnetic Theory Questions and Answers – Real Time Applications

«
»

This set of Electromagnetic Theory Multiple Choice Questions & Answers (MCQs) focuses on “Real Time Applications”.

1. In a magnetic material, always there exist magnetic dipoles as well as monopoles. State True/False.
a) True
b) False
View Answer

Answer: b
Explanation: A magnetic material possesses only magnetic dipoles. The absence of magnetic monopoles is indicated by the equation Div(B) = 0.
advertisement

2. Find the total flux in a material of flux density 15 units in an area of 24 units.
a) 3.6
b) 7.2
c) 9.6
d) 5.4
View Answer

Answer: a
Explanation: The total flux in a material is given by φ = ∫ B.dS. Put B= 15 and ∫dS = 0.24. On substituting, we get φ = 15 x 0.24 = 3.6 units.

3. Find the magnetic field intensity of a material with flux density of 24 units in air(in 106 order)
a) 19.09
b) 21
c) 25
d) 26.78
View Answer

Answer: a
Explanation: The magnetic flux density is given by B = μ H. To get H, put B = 24 and μ = 4∏ x 10-7. Thus H = 24/4∏ x 10-7 = 19.09 x 106 units.
Sanfoundry Certification Contest of the Month is Live. 100+ Subjects. Participate Now!
advertisement
advertisement

4. Find the magnetic flux density when the vector potential is a position vector.
a) 1
b) 0
c) -1
d) ∞
View Answer

Answer: b
Explanation: The magnetic flux density is given by B = Curl(A) and A = x i + y j + z k. The curl of the position vector A is i(0) – j(0) + k(0) = 0. Thus the flux density is also zero.

5. When the electric field travels in +x direction and the EM wave is travelling the –y direction, then the magnetic field will be travelling in which direction?
a) +z direction
b) –z direction
c) Either +z or –z direction
d) Does not travel
View Answer

Answer: c
Explanation: The electric field and magnetic field will always travel perpendicular to each other and the EM wave will travel perpendicular to both these fields. In the given condition when E travels in +x direction and wave in –y direction, then the H field that is perpendicular to both components will be travelling in either +z or –z direction.
advertisement

6. Inductance is present in semiconductor. State True/False.
a) True
b) False
View Answer

Answer: b
Explanation: Inductance property exists only for pure conductors like coil, solenoid, toroid etc. It is not present in semiconductors.

7. Electromagnetic waves are longitudinal in nature. State True/False.
a) True
b) False
View Answer

Answer: b
Explanation: Light and other electromagnetic radiations are transverse in nature as they travel at the same speed through a vacuum, such as through space. Such waves vibrate at right angles to the direction of propagation.
advertisement

8. Identify the devices that do not use electromagnetic energy.
a) Television
b) Washing machine
c) Microwave oven
d) Mobile phones
View Answer

Answer: b
Explanation: Television and mobile phones use the electromagnetic waves as signals. Microwave ovens generate electromagnetic waves (microwaves) for heating the food. Washing machine does not use any EM wave for its operation.

9. Find the flux density of a conductor in the square of the centre of the loop having current 3.14A and radius is 1.414m in air.
a) 8π x 10-7
b) 4π x 10-7
c) 6π x 10-7
d) 2π x 10-7
View Answer

Answer: a
Explanation: The magnetic flux density of a conductor in the square of centre of the loop is given by B = 2√2 μo I/π R. Put I = 3.14 and R = 1.414, we get B = 2 x 1.414 x 4π x 10-7 x 3.14/π x 1.414 = 8π x 10-7 units.
advertisement

10. Which type of flux will increase the inductance?
a) Series aiding
b) Series opposing
c) Shunt aiding
d) Shunt opposing
View Answer

Answer: a
Explanation: The series aiding flux will give maximum inductance to a circuit compared to any other fluxing techniques. This is because all the individual and mutual inductances will get added.

Sanfoundry Global Education & Learning Series – Electromagnetic Theory.
To practice all areas of Electromagnetic Theory, here is complete set of 1000+ Multiple Choice Questions and Answers.

advertisement
advertisement
Subscribe to our Newsletters (Subject-wise). Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Join our social networks below and stay updated with latest contests, videos, internships and jobs!

Youtube | Telegram | LinkedIn | Instagram | Facebook | Twitter | Pinterest
Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

Subscribe to his free Masterclasses at Youtube & technical discussions at Telegram SanfoundryClasses.