MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 91 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A magnetic circuit is applied with a current that changes at a rate of 5 A/sec. The circuit has an inductance of 2 H, then the self-induced EMF is: |
| A. | -4 V |
| B. | -10 V |
| C. | -2.5 V |
| D. | 0.4 V |
| Answer» C. -2.5 V | |
| 2. |
All the Three inductors are perfeclty coupled as shown below, the value of total inductance (in Henry) across the terminal AB is |
| A. | 46 |
| B. | 38 |
| C. | 12 |
| D. | 10 |
| Answer» E. | |
| 3. |
A coil is wound with 50 turns and a current of 8 A produces a flux of 200 μWb. Calculate the inductance of the coil. |
| A. | 0.25 mH |
| B. | 2.5 mH |
| C. | 1.25 mH |
| D. | 0.125 mH |
| Answer» D. 0.125 mH | |
| 4. |
Mutual inductance of the two magnetically coupled coils depends on |
| A. | Number of turns of each coil |
| B. | Flux produced by one and linked by the other |
| C. | Current in the flux producing coil |
| D. | All the above |
| Answer» E. | |
| 5. |
In the transformer circuit shown in the given figure, for maximum power transfer from source to load the turns ratio (primary to secondary) should be: |
| A. | 300 : 100 |
| B. | 100 : 300 |
| C. | 900 : 100 |
| D. | 100 : 900 |
| Answer» B. 100 : 300 | |
| 6. |
Determine the magnitude of induced EMF (in V) in a coil, it the current changes from +2 to -2A in 0.5 second and the coefficient of mutual induction is 0.5 |
| A. | 2 |
| B. | 4 |
| C. | 3 |
| D. | 6 |
| Answer» C. 3 | |
| 7. |
Match the following lists in terms of Electrical and Magnetic circuits:List-I List-II(Magnetic circuits) (Electrical circuits)(a) \(\frac{N.i}{\phi }\)(i) \(\underset{m}{\mathop \sum }\,{{V}_{m}}\)(b) \(\underset{m}{\mathop \sum }\,{{N}_{m}}.{{i}_{m}}\)(ii) \(\underset{k}{\mathop \sum }\,{{i}_{k}}=0\)(c) \(\sum {{\phi }_{k}}=0\)(iii) \(\frac{1}{p}\)(d) μ(iv) \(\frac{V}{i}\) |
| A. | a-iv, b-i, c-ii, d-iii |
| B. | a-i, b-iii, c-iv, d-ii |
| C. | a-ii, b-i, c-iii, d-iv |
| D. | a-i, b-iv, c-ii, d-iii |
| Answer» B. a-i, b-iii, c-iv, d-ii | |
| 8. |
For magnetically isolated coils, the value of coefficient of coupling is: |
| A. | 0 |
| B. | 1 |
| C. | 0.5 |
| D. | 0.75 |
| Answer» B. 1 | |
| 9. |
Find the mutual inductance between two ideally coupled coils of 2 H and 8 H. |
| A. | 16 H |
| B. | 8 H |
| C. | 4 H |
| D. | 2 H |
| Answer» D. 2 H | |
| 10. |
If two identical inductors are magnetically coupled, the mutual inductance is 10 mH and the coefficient of coupling is 0.4. Find the self – inductance of the identical inductors. |
| A. | 4 mH |
| B. | 25 mH |
| C. | 16 mH |
| D. | 20 mH |
| Answer» C. 16 mH | |
| 11. |
Energy stored in an iron cored coil is 500 Joules when carrying a certain current and at that current its copper loss is 1000 W. Time constant of the coil in seconds is: |
| A. | 4 |
| B. | 2 |
| C. | 1 |
| D. | 0.5 |
| Answer» D. 0.5 | |
| 12. |
Magneto Motive Force (MMF) is equal to |
| A. | B.I |
| B. | H.T |
| C. | N.I |
| D. | ϕ.I |
| Answer» D. ϕ.I | |
| 13. |
Find the total inductance of the series coil shown. |
| A. | 42 H |
| B. | 26 H |
| C. | 36 H |
| D. | 18 H |
| Answer» C. 36 H | |
| 14. |
Calculate the total inductance (in H) of the circuit shown below: |
| A. | 5.33 |
| B. | 8.77 |
| C. | 10.5 |
| D. | 11.9 |
| Answer» C. 10.5 | |
| 15. |
A 15 mH is connected in series with another coil. The total inductance in series addition and series opposition is 70 mH and 30 mH respectively. Find self – inductance of the second coil. |
| A. | 10 mH |
| B. | 25 mH |
| C. | 20 mH |
| D. | 35 mH |
| Answer» E. | |
| 16. |
For an amplifier the coupling method which gives the highest gain is |
| A. | transformer coupling |
| B. | resistance coupling |
| C. | impedance coupling |
| D. | capacitance coupling |
| Answer» B. resistance coupling | |
| 17. |
Permeability in a magnetic circuit corresponds to ________ in an electric circuit. |
| A. | conductivity |
| B. | resistivity |
| C. | resistance |
| D. | none of the above |
| Answer» B. resistivity | |
| 18. |
A soft iron toroid is concentric with a long straight conductor carrying a dc of I A. If μr of soft-iron is 100, find the ratio of magnetic flux densities at two adjacent points located just inside and just outside the toroid. |
| A. | 100 |
| B. | 200 |
| C. | 50 |
| D. | 500 |
| Answer» B. 200 | |
| 19. |
An analogous of magnetic circuit ‘permeability’ in electrical circuit is |
| A. | Reluctivity |
| B. | Conductance |
| C. | Conductivity |
| D. | Resistivity |
| Answer» D. Resistivity | |
| 20. |
A transformer has 350 primary turns and 1050 secondary turns. The primary winding is connected across a 230 V, 50 Hz supply. The induced EMF in the secondary will be |
| A. | 690 V, 50 Hz |
| B. | 690 V, 150 Hz |
| C. | 350 V, 150 Hz |
| D. | 115 V, 50 Hz |
| Answer» B. 690 V, 150 Hz | |
| 21. |
Find the transformer ratios a and b that the impedance \(({Z_{in}})\) is resistive and equal 2.5 Ω when the network is excited with a sine wave voltage of angular frequency of 5000 rad/s |
| A. | a = 0.5, b = 2.0 |
| B. | a = 2.0, b = 0.5 |
| C. | a = 1.0, b = 1.0 |
| D. | a = 4.0, b = 0.5 |
| Answer» C. a = 1.0, b = 1.0 | |
| 22. |
______ in a magnetic circuit is analogous to resistivity in an electrical circuit. |
| A. | Reluctivity |
| B. | Permeability |
| C. | Field intensity |
| D. | Flux density |
| Answer» B. Permeability | |
| 23. |
Mutual inductance between two closely coupled coils is 2 H. Now, if the number of turns in one coil is reduced by 50 percent and those of the other coil is doubled then, new value of mutual inductance is: |
| A. | 2 H |
| B. | 8 H |
| C. | 1 H |
| D. | 4 H |
| Answer» B. 8 H | |
| 24. |
For magnetically coupled circuits, mutual inductance is always _______. |
| A. | infinite |
| B. | negative |
| C. | positive |
| D. | zero |
| Answer» D. zero | |
| 25. |
A voltage step-up transformer with a 1 : 5 turns ratio has 220 V across 2200 ohms in the secondary. Calculate the value of primary current. |
| A. | 0.1 A |
| B. | 0.5 A |
| C. | 1.0 A |
| D. | 220 mA |
| Answer» C. 1.0 A | |
| 26. |
Determine the coupling factor between two coils each having self-inductance of 40 mH and the mutual inductance between them is 40 mH. |
| A. | 2 |
| B. | 0.5 |
| C. | 1 |
| D. | 0.75 |
| Answer» D. 0.75 | |
| 27. |
In a mutually coupled circuit, the primary current is reduced from 4 A to zero in 10 μs. A voltage of 40000 V is observed across the secondary. The mutual inductance between the coils is |
| A. | 100 H |
| B. | 10 H |
| C. | 0.1 H |
| D. | 0.01 H |
| Answer» D. 0.01 H | |
| 28. |
Calculate the mutual inductance for a system defined below.Two coils P and Q are kept in parallel planes, such that 70% of the flux produced by coil P links with coil Q. The number of turns in coil P is 10,000 and in coil Q is 12,000.A current of 4 A in coil P produces a flux of 0.04 mWb while a current of 4 A in coil Q produces a flux of 0.08 mWb. |
| A. | 1.25 H |
| B. | 0.90 H |
| C. | 0.08 H |
| D. | 3.21 H |
| Answer» D. 3.21 H | |
| 29. |
When using a fluxmeter, if the flux changes from Φ to -Φ, what happens to the current? |
| A. | Becomes zero |
| B. | Becomes infinity |
| C. | Remains the same |
| D. | Reverses |
| Answer» E. | |
| 30. |
Calculate the MMF when the magnetic flux is 5Wb and the reluctance is 3A/Wb. |
| A. | 10At |
| B. | 10N |
| C. | 15N |
| D. | 15At |
| Answer» E. | |
| 31. |
What happens to the MMF when the magnetic flux decreases? |
| A. | Increases |
| B. | Decreases |
| C. | Remains constant |
| D. | Becomes zero |
| Answer» C. Remains constant | |
| 32. |
Ohm’s law for magnetic circuits is _________ |
| A. | F=ϕS |
| B. | F=ϕ/S |
| C. | F=ϕ²S |
| D. | F=ϕ/S² |
| Answer» B. F=ϕ/S | |
| 33. |
A ring having a cross-sectional area of 500 mm², a circumference of 400 mm and ϕ=800microWb has a coil of 200 turns wound around it. Relative permeability of ring is 380. Calculate the magnetising current. |
| A. | 6.7A |
| B. | 7.7A |
| C. | 7.6 |
| D. | 6.1A |
| Answer» B. 7.7A | |
| 34. |
A ring having a cross-sectional area of 500 mm², a circumference of 400 mm and ϕ=800microWb has a coil of 200 turns wound around it. Relative permeability of ring is 380. Calculate the magnetomotive force. |
| A. | 1442At |
| B. | 1342At |
| C. | 1432At |
| D. | 1344At |
| Answer» E. | |
| 35. |
Can we apply Kirchhoff’s law to magnetic circuits? |
| A. | Yes |
| B. | No |
| C. | Depends on the circuit |
| D. | Insufficient information provided |
| Answer» B. No | |
| 36. |
A ring having a cross-sectional area of 500 mm², a circumference of 400 mm and ϕ=800microWb has a coil of 200 turns wound around it. Calculate the flux density of the ring. |
| A. | 1.6T |
| B. | 2.6T |
| C. | 3.6T |
| D. | 4.6T |
| Answer» B. 2.6T | |
| 37. |
A ring having a cross-sectional area of 500 mm², a circumference of 400 mm and ϕ=800microWb has a coil of 200 turns wound around it. Relative permeability of ring is 380. Calculate the reluctance. |
| A. | 1.68 * 10¯⁴A/Wb |
| B. | 1.68 * 10⁴ A/Wb |
| C. | 1.68 * 10⁶ A/Wb |
| D. | 1.68 * 10¯⁶A/Wb |
| Answer» D. 1.68 * 10¯⁶A/Wb | |
| 38. |
When an electric current flows into the page, what is the direction of the magnetic field? |
| A. | Clockwise |
| B. | Anti-clockwise |
| C. | Cannot be determined |
| D. | Parallel to the current |
| Answer» B. Anti-clockwise | |
| 39. |
When a bar magnet is broken into two pieces, which of the following are true? |
| A. | The magnet loses its magnetism |
| B. | The magnet has only north pole left |
| C. | The magnet has only south pole left |
| D. | The magnet turns into two new bar magnets |
| Answer» E. | |
| 40. |
The unit for permeability of free space is? |
| A. | Henry |
| B. | Henry-m |
| C. | Henry/m |
| D. | Henry/m² |
| Answer» D. Henry/m² | |
| 41. |
A substance whose permeability is less than the permeability of free space is? |
| A. | Diamagnetic |
| B. | Paramagnetic |
| C. | Ferromagnetic |
| D. | Not a magnetic substance |
| Answer» B. Paramagnetic | |
| 42. |
What is the unit for relative permeability? |
| A. | H-m |
| B. | H/m |
| C. | H²/m |
| D. | No unit |
| Answer» E. | |
| 43. |
Which, among the following, have negative susceptibility? |
| A. | Diamagnetic |
| B. | Paramagnetic |
| C. | Ferromagnetic |
| D. | Not a magnetic substance |
| Answer» B. Paramagnetic | |
| 44. |
Reciprocal of reluctance is __________ |
| A. | Permeance |
| B. | Susceptibility |
| C. | Resistance |
| D. | Conductance |
| Answer» B. Susceptibility | |
| 45. |
As the temperature increases up to the Curie temperature, the relative susceptibility of ferromagnetic materials? |
| A. | Increases |
| B. | Decreases |
| C. | Remains constant |
| D. | Becomes zero |
| Answer» B. Decreases | |
| 46. |
Unit of reluctance is? |
| A. | AWb |
| B. | A²/Wb |
| C. | Wb/A |
| D. | A/Wb |
| Answer» E. | |
| 47. |
When the area of cross section of the material increases, what happens to reluctance? |
| A. | Increases |
| B. | Decreases |
| C. | Remains the same |
| D. | Becomes zero |
| Answer» C. Remains the same | |
| 48. |
As the magnetic field strength increases, reluctance? |
| A. | Increases |
| B. | Decreases |
| C. | Remains the same |
| D. | Becomes zero |
| Answer» B. Decreases | |
| 49. |
The electrical equivalent of reluctance is? |
| A. | Resistance |
| B. | Inductance |
| C. | Capacitance |
| D. | Conductance |
| Answer» B. Inductance | |
| 50. |
When the length of the material increases, what happens to reluctance? |
| A. | Increases |
| B. | Decreases |
| C. | Remains the same |
| D. | Becomes zero |
| Answer» B. Decreases | |