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MCQOPTIONS
This section includes 1085 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A conductor carries 125 amperes of current under 60° to a magnetic field of 1.1 tesla.The force on the conductor will be nearly |
| A. | 50 N |
| B. | 120 N |
| C. | 240 N |
| D. | 480 N |
| Answer» C. 240 N | |
| 2. |
When a dielectric slab is introduced in a parallel plate capacitor, the potential differencebetween plates will |
| A. | remain uncharged |
| B. | decrease |
| C. | increase |
| D. | become zero |
| Answer» C. increase | |
| 3. |
If the sheet of a bakelite is inserted between the plates of an air capacitor, thecapacitance will |
| A. | decrease |
| B. | increase |
| C. | remains unchanged |
| D. | become zero |
| Answer» C. remains unchanged | |
| 4. |
The working of a meter is based on the use of a permanent magnet. In order to protectthe 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 | |
| 5. |
at a point may be defined as equal to the lines of force passing normally through a unitcross section at that point. |
| A. | Electric intensity |
| B. | Magnetic flux density |
| C. | Electric flux |
| D. | None of the above |
| Answer» B. Magnetic flux density | |
| 6. |
Three capacitors each of the capacity C are given. The resultant capacity 2/3 Ccan be obtained by using them |
| A. | all in series |
| B. | all in parallel |
| C. | two in parallel and third in series with this combination |
| D. | two in series and third in parallel across this combination |
| Answer» D. two in series and third in parallel across this combination | |
| 7. |
Two infinitely long parallel conductors in vacuum anf' separated 1 metre between centres >rhen a current of 1 ampere flows thn. ugh each conductor, produce on each otLer 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. | |
| 8. |
A coil is wound on iron core which carries current I. The self-induced voltage in the coilis not affected by |
| A. | variation in coil current |
| B. | variation in voltage to the coil |
| C. | change of number of turns of coil |
| D. | the resistance of magnetic path |
| Answer» C. change of number of turns of coil | |
| 9. |
The time constant and R-C circuit may also be defined as the time during which thecharging current falls to ______ percent of its initial maximum value, |
| A. | 37 |
| B. | 42 |
| C. | 63 |
| D. | 73 |
| Answer» B. 42 | |
| 10. |
A coil induces 350 mV when the current changes at the rate of 1 A/s. The value ofinductance is |
| A. | 3500 mH |
| B. | 350 mH |
| C. | 250 mH |
| D. | 150 mH |
| Answer» C. 250 mH | |
| 11. |
The Biot-savart's law is a general modification of |
| A. | Kirchhoffs law |
| B. | Lenz's law |
| C. | Ampere's law |
| D. | Faraday's laws |
| Answer» D. Faraday's laws | |
| 12. |
In a capacitor, the electric charge is stored in |
| A. | metal plates |
| B. | dielectric |
| C. | dielectric as well as metal plates |
| D. | none of the above |
| Answer» C. dielectric as well as metal plates | |
| 13. |
Current changing from 8 A to 12 A in one second induced 20 volts in a coil.The value of inductance is |
| A. | 5 mH |
| B. | 10 mH |
| C. | 5 H |
| D. | 10 H |
| Answer» D. 10 H | |
| 14. |
The initial rate of rise of current through a coil of inductance 10 H when suddenlyconnected to a D.C. supply of 200 V is_______Vs |
| A. | 50 |
| B. | 20 |
| C. | 0.05 |
| D. | 500 |
| Answer» C. 0.05 | |
| 15. |
For a purely inductive circuit which of the following is true ? |
| A. | Apparent power is zero |
| B. | Relative power is.zero |
| C. | Actual power of the circuit is zero |
| D. | Any capacitance even if present in the circuit will not be charged |
| Answer» D. Any capacitance even if present in the circuit will not be charged | |
| 16. |
How does the magnetic compass needle behave in a magnetic field ? |
| A. | It assures a position right angle to magnetic field |
| B. | It starts rotating |
| C. | It assures a position which follows a line of magnetic flux |
| D. | None of the above |
| Answer» D. None of the above | |
| 17. |
Mica capacitors are characterised by all of thte following except |
| A. | stable operation |
| B. | accurate value |
| C. | low leakage reactance |
| D. | low losses |
| Answer» D. low losses | |
| 18. |
The time constant of an R-C circuit is defined as the time during which capacitorcharging voltage actually rises to ______ percent of its______value. |
| A. | 37, initial |
| B. | 63.2, initial |
| C. | 63.2, final |
| D. | 37, final |
| Answer» D. 37, final | |
| 19. |
The core of a coil has a length of 200 mm. The inductance of coil is 6 mH. If the corelength is doubled, all other quantities, remaining the same, the in ductance will be |
| A. | 3 mH |
| B. | 12 mH |
| C. | 24mH |
| D. | 48mH |
| Answer» B. 12 mH | |
| 20. |
Those magnetic materials are best suited for making armature and transformer coreswhich have____permeability and_______hystersis loss. |
| A. | high, high |
| B. | low, high |
| C. | high, low |
| D. | low, low |
| Answer» D. low, low | |
| 21. |
A capacitor in a circuit became hot and ultimately exploded due to wrong con¬nections,which type of capacitor it could be ? |
| A. | Paper capacitor |
| B. | Ceramic capacitor |
| C. | Electrolytic capacitor |
| D. | Any-of the above |
| Answer» D. Any-of the above | |
| 22. |
The co-efficient of coupling between two air core coils depends on |
| A. | self-inductance of two coils only |
| B. | mutual inductance between two coils only |
| C. | mutual inductance and self inductance of two coils |
| D. | none of the above |
| Answer» D. none of the above | |
| 23. |
A conductor of length L has current I passing through it, when it is placed parallel to amagnetic field. The force experienced by the conductor will be |
| A. | zero |
| B. | BLI |
| C. | B2LI |
| D. | BLI2 |
| Answer» B. BLI | |
| 24. |
1 volt/metre is same as |
| A. | 1 metre/coulomb |
| B. | 1 newton metre |
| C. | 1 newton/metre |
| D. | 1 joule/coulomb |
| Answer» D. 1 joule/coulomb | |
| 25. |
Which of the following is unit of inductance ? |
| A. | Ohm |
| B. | Henry |
| C. | Ampere turns |
| D. | Webers/metre |
| Answer» C. Ampere turns | |
| 26. |
A capacitance of 100 fiF is connected in series with a resistance of 8000 £2. The timeconstant of the circuit is |
| A. | 0.2 s |
| B. | 0.4 s |
| C. | 0.6 s |
| D. | 0.8 s |
| Answer» E. | |
| 27. |
What will be the current passing through the ring shaped air cored coil when number ofturns is 800 and ampere turns are 3200 ? |
| A. | 2 |
| B. | 4 |
| C. | 6 |
| D. | 8 |
| Answer» C. 6 | |
| 28. |
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 | |
| 29. |
A mica capacitor and a ceramic capacitor both have the same physical dimensions.Which will have more value of capacitance ? |
| A. | Ceramic capacitor |
| B. | Mica capacitor |
| C. | Both will have identical value of capacitance |
| D. | It depends on applied voltage |
| Answer» B. Mica capacitor | |
| 30. |
Both the number of turns and the core length of an inductive coil are doubled.Its self-inductance will be |
| A. | unaffected |
| B. | doubled |
| C. | halved |
| D. | quadrupled |
| Answer» C. halved | |
| 31. |
What is the value of capacitance that must be connected in parallel with 50 pFcondenser to make an equivalent capacitance of 150 pF ? |
| A. | 50 pF |
| B. | 100 pF |
| C. | 150 pF |
| D. | 200 pF |
| Answer» C. 150 pF | |
| 32. |
In case all the flux from the current in coil 1 links with coil 2, the co-efficient of couplingwill be |
| A. | 2.0 |
| B. | 1.0 |
| C. | 0.5 |
| D. | zero |
| Answer» C. 0.5 | |
| 33. |
A 500 turns solenoid develops an average induced voltage of 60 V. Over what timeinterval must a flux change of 0.06 Wb occur to produce such a voltage ? |
| A. | 0.01 s |
| B. | 0.1 s |
| C. | 0.5 s |
| D. | 5 s |
| Answer» D. 5 s | |
| 34. |
The ability of charged bodies to exert force on 6ne another is attributed to the existenceof |
| A. | electrons |
| B. | protons |
| C. | neutrons |
| D. | electric field |
| Answer» E. | |
| 35. |
The direction of incViced e.m.f. can be found by |
| A. | Laplace's law |
| B. | Lenz's law |
| C. | Fleming's right hand rule |
| D. | Kirchhoff s voltage law |
| Answer» C. Fleming's right hand rule | |
| 36. |
Two infinite parallel plates 10 mm apart have maintained between them a potentialdifference of 100 V. The acceleration of an electron placed between them is |
| A. | 0.56 x 1015 m/s2 |
| B. | 1.5 x 1015 m/s2 |
| C. | 1.6 x 1015 m/s2 |
| D. | 1.76 x 1015 m/s2 |
| Answer» E. | |
| 37. |
Substances which have permeability less than the permeability of free space are knownas |
| A. | ferromagnetic |
| B. | paramagnetic |
| C. | diamagnetic |
| D. | bipolar |
| Answer» D. bipolar | |
| 38. |
Which of the following circuit elements will oppose the change in circuit current ? |
| A. | Capacitance |
| B. | Inductance |
| C. | Resistance |
| D. | All of the above |
| Answer» C. Resistance | |
| 39. |
Mutually inductance between two magnetically-coupled coils depends on |
| A. | permeability of the core |
| B. | the number of their turns |
| C. | cross-sectional area of their com-mon core |
| D. | all of the above |
| Answer» E. | |
| 40. |
The potential gradient across the material of low permittivity is than across thematerial of high permittivity. |
| A. | smaller |
| B. | greater |
| C. | both (a) and (b) |
| D. | none of the above |
| Answer» C. both (a) and (b) | |
| 41. |
If a third equal and similar charge is placed between two equal and similar charges,then this third charge will |
| A. | move out of the field of influence of the two charges |
| B. | remain in stable equilibrium |
| C. | not be in equilibrium |
| D. | be in unstable equilibrium |
| Answer» C. not be in equilibrium | |
| 42. |
The self inductances of two coils are 8 mH and 18 mH. If the co-efficients of coupling is0.5, the mutual inductance of the coils is |
| A. | 4 mH |
| B. | 5 mH |
| C. | 6 mH |
| D. | 12 mH |
| Answer» D. 12 mH | |
| 43. |
Two coils have inductances of 8 mH and 18 mH and a co-efficient of coupling of 0.5. Ifthe two coils are connected in series aiding, the total inductance will be |
| A. | 32 mH |
| B. | 38 mH |
| C. | 40 mH |
| D. | 48 mH |
| Answer» C. 40 mH | |
| 44. |
As per Faraday's laws of electromagnetic induction, an e.m.f. is induced in a conductorwhenever it |
| A. | lies perpendicular to the magnetic flux |
| B. | lies in a magnetic field |
| C. | cuts magnetic flux |
| D. | moves parallel to the direction of the magnetic field |
| Answer» D. moves parallel to the direction of the magnetic field | |
| 45. |
The phenomenon of an uncharged body getting charged merely by the nearness of acharged body is known as |
| A. | pholoelectric effect |
| B. | chemical effect |
| C. | magnetic effect |
| D. | induction |
| Answer» E. | |
| 46. |
Which of the following is a vector quantity ? |
| A. | Relative permeability |
| B. | Magnetic field intensity |
| C. | Flux density |
| D. | Magnetic potential |
| Answer» C. Flux density | |
| 47. |
If A.C. voltage is applied to capacitive circuit, the alternating current can flow in thecircuit because |
| A. | varying voltage produces the charg¬ing and dicharging currents |
| B. | of high peak value |
| C. | charging current can flow |
| D. | discharge current can flow |
| Answer» B. of high peak value | |
| 48. |
A capacitor having capacitance of 5 uF is charged to a potential difference of 10,000 V.The energy stored in the capacitor is |
| A. | 50 joules |
| B. | 150 joules |
| C. | 200 joules |
| D. | 250 joules |
| Answer» E. | |
| 49. |
A conductor 2 metres long moves at right angles to a magnetic field of flux density 1tesla with a velocity of 12.5 m/s. The induced e.m.f. in the conductor will be |
| A. | 10 V |
| B. | 15 V |
| C. | 25V |
| D. | 50V |
| Answer» D. 50V | |
| 50. |
"The total electric flux through any closed surface surrounding charges is equal to theamount oflcharge enclosed". The above statement is associated with |
| A. | Coulomb's square law |
| B. | Gauss's law |
| C. | Maxwell's first law |
| D. | Maxwell's second law |
| Answer» C. Maxwell's first law | |