MCQOPTIONS
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MCQOPTIONS
This section includes 120 Mcqs, each offering curated multiple-choice questions to sharpen your Electromagnetic Theory knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
A short-circuited rectangular coil falls under gravity with the coil remaining in a vertical plane and cutting perpendicular horizontal magnetic lines of force. It has __________ acceleration. |
| A. | zero |
| B. | increasing |
| C. | decreasing |
| D. | constant |
| Answer» E. | |
| 102. |
Magnetic flux density is also known as ______. |
| A. | magnetic induction |
| B. | reluctance |
| C. | reluctivity |
| D. | permeance |
| Answer» B. reluctance | |
| 103. |
Ballistic test used in magnetic measurements for: |
| A. | Determination of hysteresis loop of the specimen only |
| B. | Determination of flux density, magnetizing force and B-H curve and hysteresis loop of the specimen |
| C. | Finding out iron losses in the specimen |
| D. | Determination of B-H curve of the specimen only |
| Answer» C. Finding out iron losses in the specimen | |
| 104. |
____ law states that the induced current always develops a flux which _____ the very cause it is due to. |
| A. | Ohm’s, aids |
| B. | Faraday’s, aids |
| C. | Lenz, opposes |
| D. | Fleming’s, aids |
| Answer» D. Fleming’s, aids | |
| 105. |
A wire of length 50 cm moves at right angles to its length at 50 m/s in a uniform magnetic field of density 1 Wb/m2. Determine the emf induced in the conductor when the direction of motion is perpendicular to the field. |
| A. | 250 V |
| B. | 25 V |
| C. | 15 V |
| D. | 2.5 V |
| Answer» C. 15 V | |
| 106. |
Determined the self-inductance (in mH) of a 4 m long air cored solenoid, if the solenoid has a cross sectional area of 0.02 square meter and has 60 turns. |
| A. | 0.064 |
| B. | 0.036 |
| C. | 0.045 |
| D. | 0.023 |
| Answer» E. | |
| 107. |
A magnet is kept in the medium of air surrounded by an iron ring. The magnetic lines of force from the magnet will be |
| A. | Very small in the ring |
| B. | Crowded in the ring |
| C. | Passing out of the ring |
| D. | Evenly distributed within the ring |
| Answer» C. Passing out of the ring | |
| 108. |
Hysteresis loss is ________ proportional to the area under the hysteresis curve. Also, it is ________ proportional to the number of cycles of magnetization per second: |
| A. | Directly, inversely |
| B. | Inversely, directly |
| C. | Directly, directly |
| D. | Inversely, inversely |
| Answer» D. Inversely, inversely | |
| 109. |
Calculate the inductance of coil which is wounded uniformly on an iron core. Given:Relative permeability of the iron: 1400Length of the magnetic circuit: 70 cmThe cross-sectional area of the core: 5 cm2Number of turns: 1000 |
| A. | 2.53 H |
| B. | 8.24 H |
| C. | 1.25 H |
| D. | 3.56 H |
| Answer» D. 3.56 H | |
| 110. |
Determine the magnitude of magnetic field (in mT) at the center of a 50 cm long solenoid, if the solenoid has 300 turns and carrying a current of 5 A. |
| A. | 2.61 |
| B. | 2.66 |
| C. | 4.64 |
| D. | 3.77 |
| Answer» E. | |
| 111. |
A 4 cm long coil has 8 turns and carries a current of 500 mA. The magnetising force of the coil is: |
| A. | 500 AT/m |
| B. | 10 AT/m |
| C. | 100 AT/m |
| D. | 1000 AT/m |
| Answer» D. 1000 AT/m | |
| 112. |
Determine the produced mmf (in Amp-truns) in a magnetic circuit if it has 60 turns and carrying a current of 0.5 A. |
| A. | 10 |
| B. | 20 |
| C. | 30 |
| D. | 40 |
| Answer» D. 40 | |
| 113. |
Four relations have been given. Select the correct relation. |
| A. | MMF = Flux/Permeance |
| B. | MMF = Flux/Reluctance and Flux = MMF/Permeance |
| C. | Flux = MMF/Permeance |
| D. | MMF = Flux/Reluctance |
| Answer» B. MMF = Flux/Reluctance and Flux = MMF/Permeance | |
| 114. |
Current passing through an inductor is 4 A. Energy stored in the inductor of inductance 0.2 Henry will be: |
| A. | 0.8 J |
| B. | 8 J |
| C. | 1.6 J |
| D. | 0.16 J |
| Answer» D. 0.16 J | |
| 115. |
A certain flux meter has the following specifications:Air gap flux density = 0.05 Wb/m2Number of turns on moving coil = 40Area of moving coil = 750 mm2If the flux linking 10 turns of a search coil of 200 mm2 area connected to the flux meter is reversed in a uniform field of 0.5 Wb/m2, then the deflection of the flux meter will be |
| A. | 87.4° |
| B. | 76.5° |
| C. | 65.6° |
| D. | 54.7° |
| Answer» C. 65.6° | |
| 116. |
A flux of 2 mWb passes through a strip of length and breadth 10 cm and 20 cm respectively. It is placed at an angle of 30 degrees to the direction of uniform magnetic field. What is the magnetic flux density (in T)? |
| A. | 0.1 |
| B. | 0.115 |
| C. | 0.9 |
| D. | 1 |
| Answer» C. 0.9 | |
| 117. |
Determine the flux (in Wb) through a coil when the reluctance of the coil is 4 Amp-turns/Wb and the produced mmf is 48 Amp-turns. |
| A. | 10 |
| B. | 12 |
| C. | 14 |
| D. | 16 |
| Answer» C. 14 | |
| 118. |
Find H = ___________ A/m at the center of a circular coil of diameter 1 m and carrying a current of 2 A. |
| A. | 0.6366 |
| B. | 0.1636 |
| C. | 6.366 |
| D. | 2 |
| Answer» E. | |
| 119. |
Determine the current required in a 400 mm length of conductor of an electric motor, when the conductor is situated at right-angle to a magnetic field flux density 1.2T, if force of 1.92 N is to be exerted on the conductor. |
| A. | 8 A |
| B. | 6 A |
| C. | 4 A |
| D. | 2 A |
| Answer» D. 2 A | |
| 120. |
In the circuit shown, what is the reluctance (R) as seen from coil N1? |
| A. | R = (Rg1 || Rg2) + Rg |
| B. | R = (Rg1 + Rg2) || Rg3 |
| C. | R = Rg1 + Rg2 + Rg3 |
| D. | R = Rg1 + (Rg2 || Rg3) |
| Answer» E. | |