MCQOPTIONS
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MCQOPTIONS
This section includes 110 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
When the south poles of two bar magnets are brought close together, there will be a force of attraction. |
| A. | True |
| B. | False |
| Answer» C. | |
| 2. |
The unit of magnetic flux is the . |
| A. | True |
| B. | False |
| Answer» B. False | |
| 3. |
A magnetic field is produced around a current-carrying conductor. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 4. |
Which electromagnetic device has a flexible ? |
| A. | A speaker |
| B. | A dc generator |
| C. | A relay |
| D. | A solenoid |
| Answer» B. A dc generator | |
| 5. |
What is the reluctance of a material that has a length of 0.045 m, a cross-sectional area of 0.015 m, and a permeability of 2500 µWb/At·m? |
| A. | 833.33 µAt/Wb |
| B. | 0.27 At/Wb |
| C. | 1200 At/Wb |
| D. | More information is needed in order to find the reluctance. |
| Answer» D. More information is needed in order to find the reluctance. | |
| 6. |
Which two values are plotted on a curve graph? |
| A. | Reluctance and flux density |
| B. | Permeability and reluctance |
| C. | Magnetizing force and permeability |
| D. | Flux density and magnetizing force |
| Answer» E. | |
| 7. |
The operation of an electrical generator relies on . |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8. |
Which electromagnetic device has a movable iron core called a ? |
| A. | A speaker |
| B. | A dc generator |
| C. | A relay |
| D. | A solenoid |
| Answer» E. | |
| 9. |
Which electromagnetic device contains an ? |
| A. | A speaker |
| B. | A dc generator |
| C. | A relay |
| D. | A solenoid |
| Answer» C. A relay | |
| 10. |
When the current through a coil reverses direction, the magnetic field around the coil _____. |
| A. | does not change |
| B. | disappears |
| C. | increases in strength |
| D. | reverses direction |
| Answer» E. | |
| 11. |
The flux density is ___ when the magnetic flux is 9 µWb and the cross-sectional area of the magnetic field is 5 × 10 m. |
| A. | 1800 µT |
| B. | 555.56 T |
| C. | 9 µT |
| D. | 5 × 10 |
| E. | T |
| Answer» B. 555.56 T | |
| 12. |
The movable part in a relay is the _____. |
| A. | plunger |
| B. | armature |
| C. | cone |
| D. | brushes |
| Answer» C. cone | |
| 13. |
The unit of magnetic flux density is the . |
| A. | True |
| B. | False |
| Answer» C. | |
| 14. |
The ability of a material to maintain a magnetized state (without the presence of a magnetizing force) is called . |
| A. | True |
| B. | False |
| Answer» B. False | |
| 15. |
Which electromagnetic device uses and a ? |
| A. | A speaker |
| B. | A dc generator |
| C. | A relay |
| D. | A solenoid |
| Answer» C. A relay | |
| 16. |
What is the flux density of a magnetic field whose flux is 3000 µWb and cross-sectional area is 0.25 m? |
| A. | 12,000 |
| B. | T |
| C. | 83,330 T |
| D. | 0 T |
| E. | More information is needed in order to find flux density. |
| Answer» B. T | |
| 17. |
The flux density is ___ when the magnetic flux is 9 µWb and the cross-sectional area of the magnetic field is 5 × 10–3 m2. |
| A. | 1800 µT |
| B. | 555.56 T |
| C. | 9 µT |
| D. | 5 × 10–3 T |
| Answer» B. 555.56 T | |
| 18. |
What is the reluctance of a material that has a length of 0.045 m, a cross-sectional area of 0.015 m2, and a permeability of 2500 µWb/At·m? |
| A. | 833.33 µAt/Wb |
| B. | 0.27 At/Wb |
| C. | 1200 At/Wb |
| D. | More information is needed in order to find the reluctance. |
| Answer» D. More information is needed in order to find the reluctance. | |
| 19. |
What is the flux density of a magnetic field whose flux is 3000 µWb and cross-sectional area is 0.25 m2? |
| A. | 12,000 T |
| B. | 83,330 T |
| C. | 0 T |
| D. | More information is needed in order to find flux density. |
| Answer» B. 83,330 T | |
| 20. |
Ampere-turn is the unit of magnetomotive force (mmf). |
| A. | True |
| B. | False |
| Answer» B. False | |
| 21. |
Hysteresis is the number of lines of force per unit area in a magnetic field. |
| A. | True |
| B. | False |
| Answer» C. | |
| 22. |
Reluctance in a magnetic circuit is analogous to current in an electrical circuit. |
| A. | True |
| B. | False |
| Answer» C. | |
| 23. |
A magnetic field is made up of flux lines. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 24. |
Electromagnetic induction is the force that produces a magnetic field. |
| A. | True |
| B. | False |
| Answer» C. | |
| 25. |
A relay is an electromagnetically controlled mechanical device in which electrical contacts are opened or closed by a magnetizing current. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 26. |
The tesla is the unit of magnetic flux. |
| A. | True |
| B. | False |
| Answer» C. | |
| 27. |
What is the reluctance of a material that has a length of 0.07 m, a cross-sectional area of 0.014 m2, and a permeability of 4,500 Wb/At × m? |
| A. | 1111 At/Wb |
| B. | 111 At/Wb |
| C. | 11 At/Wb |
| D. | 1 At/Wb |
| Answer» B. 111 At/Wb | |
| 28. |
What is the flux density when the flux is 5.5 Wb and the cross-sectional area is 6 × 10–3 m2? |
| A. | 91.7 T |
| B. | 917 T |
| C. | 91 T |
| D. | 9.7 T |
| Answer» C. 91 T | |
| 29. |
Fleming’s left-hand rule hand is applicable to |
| A. | DC generator |
| B. | DC motor |
| C. | Alternator |
| D. | Transformer |
| Answer» C. Alternator | |
| 30. |
Magnetic permeability is maximum for ______ material. |
| A. | Diamagnetic |
| B. | Paramagnetic |
| C. | Ferromagnetic |
| D. | None of the above |
| Answer» D. None of the above | |
| 31. |
A rectangular magnet of magnetic moment M is cut into two piece of same length, the magnetic moment of each piece will be |
| A. | M |
| B. | M/2 |
| C. | 2 M |
| D. | M/4 |
| Answer» C. 2 M | |
| 32. |
The magnetic materials exhibit the property of magnetisation because of |
| A. | orbital motion of electrons |
| B. | spin of electrons |
| C. | spin of nucleus |
| D. | either of these |
| Answer» D. either of these | |
| 33. |
Which of the following type of materials are not very important for engineering applications? |
| A. | Ferromagnetic |
| B. | Paramagnetic |
| C. | Diamagnetic |
| D. | None of the above |
| Answer» D. None of the above | |
| 34. |
What will be the current passing through the ring shaped air cored coil when number of turns is 800 and ampere turns are 3200? |
| A. | 2 |
| B. | 4 |
| C. | 6 |
| D. | 8 |
| Answer» C. 6 | |
| 35. |
The Biotsavart's law is a general modification of |
| A. | Kirchhoff's law |
| B. | Lenz's law |
| C. | Ampere's law |
| D. | Faraday's laws |
| Answer» D. Faraday's laws | |
| 36. |
For a given wire-wound core, an increase in current through the coil |
| A. | Reverses the flux lines |
| B. | Decreases the flux density |
| C. | Increases the flux density |
| D. | Causes no change in flux density |
| Answer» D. Causes no change in flux density | |
| 37. |
For which of the following materials the net magnetic moment should be zero? |
| A. | Diamagnetic materials |
| B. | Ferrimagnetic materials |
| C. | Antiferromagnetic materials |
| D. | Antiferrimagnetic materials |
| Answer» D. Antiferrimagnetic materials | |
| 38. |
In a simple magnetic field the strength of magnet flux |
| A. | is constant and has same value in energy part of the magnetic field |
| B. | increases continuously from initial value to final value |
| C. | decreases continuously from initial value to final value |
| D. | first increases and then decreases till it becomes zero |
| Answer» E. | |
| 39. |
A square cross-sectional magnet has a pole strength of 1 x 10 Wb and cross sectional area of 20 mm x 20 mm. What is the strength at a distance of 100 mm from the unit pole in air ? |
| A. | 63.38 N/Wb |
| B. | 633.8 N/Wb |
| C. | 6338 N/Wb |
| D. | 63380 N/Wb |
| Answer» D. 63380 N/Wb | |
| 40. |
Substances which have permeability less than the permeability of free space are known as |
| A. | Ferromagnetic |
| B. | Paramagnetic |
| C. | Diamagnetic |
| D. | Bipolar |
| Answer» D. Bipolar | |
| 41. |
The magnetic reluctance of a material |
| A. | decreases with increasing cross sectional area of material |
| B. | increases with increasing cross-sec-tional area of material |
| C. | does not vary with increasing cross-sectional area of material |
| D. | any of the above |
| Answer» B. increases with increasing cross-sec-tional area of material | |
| 42. |
Two long parallel conductors carry 100 A. If the conductors are separated by 20 mm, the force per meter of length of each conductor will be |
| A. | 100 N |
| B. | 10 N |
| C. | 1 N |
| D. | 0.1 N |
| Answer» E. | |
| 43. |
When two ends of a circular uniform wire are joined to the terminals of a battery, the field at the center of the circle |
| A. | will be zero |
| B. | will be infinite |
| C. | will depend on the amount of e.m.f. applied |
| D. | will depend on the radius of the circle |
| Answer» E. | |
| 44. |
A permeable substance is one |
| A. | which is a good conductor |
| B. | which is a bad conductor |
| C. | which is a strong magnet |
| D. | through which the magnetic lines of force can pass very easily |
| Answer» E. | |
| 45. |
Hysteresis loop in case of magnetically hard materials is more in shape as compared to magnetically soft materials. |
| A. | circular |
| B. | triangular |
| C. | rectangular |
| D. | none of the above |
| Answer» D. none of the above | |
| 46. |
A coil of wire is placed in a changing magnetic field. If the number of turns in the coil is decreased, the voltage induced across the coil will |
| A. | Increase |
| B. | Decrease |
| C. | Remain constant |
| D. | Be excessive |
| Answer» C. Remain constant | |
| 47. |
Two infinitely long parallel conductors in vacuum any separated 1 metre between centers >then a current of 1 ampere flows the. uk each conductor, produce on each other a force of |
| A. | 2 x 1(T2 N/m) |
| B. | 2 x KT3 N/m |
| C. | 2 x 10"5 N/m |
| D. | 2x 1(T7 N/m) |
| Answer» E. | |
| 48. |
If the steel disk in a crankshaft position sensor has stopped with the tab in the magnet's air gap, the induced voltage |
| A. | Increases |
| B. | Decreases |
| C. | Is zero |
| D. | Will remain constant |
| Answer» D. Will remain constant | |
| 49. |
What will be the magnetic potential difference across the air gap of 2 cm length in magnetic field of 200 AT/m? |
| A. | 2 AT |
| B. | 4 AT |
| C. | 6 AT |
| D. | 10 AT |
| Answer» C. 6 AT | |
| 50. |
The working of a meter is based on the use of a permanent magnet. In order to protect the meter functioning from stray magnetic fields |
| A. | meter is surrounded by strong magnetic fields |
| B. | a soft iron shielding is used |
| C. | a plastic shielding is provided |
| D. | a shielding of anon-magnetic material is used |
| Answer» C. a plastic shielding is provided | |