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This set of Electromagnetics Multiple Choice Questions & Answers (MCQs) focuses on Electromagnetics Set 18

Q1 | 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
  • 4 mh
  • 5 mh
  • 6 mh
  • 12 mh
Q2 | 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
  • 32 mh
  • 38 mh
  • 40 mh
  • 48 mh
Q3 | A 200 turn coil has an inductance of 12 mH. If the number of turns is increased to 400turns, all other quantities (area, length etc.) remaining the same, the inductance will be
  • 6 mh
  • 14 mh
  • 24 mh
  • 48 mh
Q4 | Two coils have self-inductances of 10 H and 2 H, the mutual inductance being zero. Ifthe two coils are connected in series, the total inductance will be
  • 6 h
  • 8 h
  • 12 h
  • 24 h
Q5 | In case all the flux from the current in coil 1 links with coil 2, the co-efficient of couplingwill be
  • 2.0
  • 1.0
  • 0.5
  • zero
Q6 | A coil with negligible resistance has 50V across it with 10 mA. The inductive reactanceis
  • 50 ohms
  • 500 ohms
  • 1000 ohms
  • 5000 ohms
Q7 | Lenz's law is a consequence of the law of conservation of
  • induced current
  • charge
  • energy
  • induced e.m.f.
Q8 | 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
  • 50 n
  • 120 n
  • 240 n
  • 480 n
Q9 | Find the force acting on a conductor 3m long carrying a current of 50 amperes at rightangles to a magnetic field having a flux density of 0.67 tesla.
  • 100 n
  • 400 n
  • 600 n
  • 1000 n
Q10 | The co-efficient of coupling between two air core coils depends on
  • self-inductance of two coils only
  • mutual inductance between two coils only
  • mutual inductance and self inductance of two coils
  • none of the above
Q11 | An average voltage of 10 V is induced in a 250 turns solenoid as a result of a change influx which occurs in 0.5 second. The total flux change is
  • 20 wb
  • 2 wb
  • 0.2 wb
  • 0.02 wb
Q12 | 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 ?
  • 0.01 s
  • 0.1 s
  • 0.5 s
  • 5 s
Q13 | Which of the fpllowing inductor will have the least eddy current losses ?
  • air core
  • laminated iron core
  • iron core
  • powdered iron core
Q14 | A coil induces 350 mV when the current changes at the rate of 1 A/s. The value ofinductance is
  • 3500 mh
  • 350 mh
  • 250 mh
  • 150 mh
Q15 | Two 300 uH coils in series without mutual coupling have a total inductance of
  • 300 uh
  • 600 uh
  • 150 uh
  • 75 uh
Q16 | Current changing from 8 A to 12 A in one second induced 20 volts in a coil.The value of inductance is
  • 5 mh
  • 10 mh
  • 5 h
  • 10 h
Q17 | Which circuit element(s) will oppose the change in circuit current ?
  • resistance only
  • inductance only
  • capacitance only
  • inductance and capacitance
Q18 | A crack in the magnetic path of an inductor will result in
  • unchanged inductance
  • increased inductance
  • zero inductance
  • reduced inductance
Q19 | A coil is wound on iron core which carries current I. The self-induced voltage in the coilis not affected by
  • variation in coil current
  • variation in voltage to the coil
  • change of number of turns of coil
  • the resistance of magnetic path
Q20 | Which of the following parameters is not a primary parameter?
  • resistance
  • attenuation constant
  • capacitance
  • conductance
Q21 | The networks in which the R, L, C parameters are individually concentrated orlumped at discrete points in the circuit are called
  • lumped
  • distributed
  • parallel
  • paired
Q22 | The lines having R, L, C distributed along the circuit are called
  • lumped
  • distributed
  • parallel
  • paired
Q23 | Which primary parameter is uniformly distributed along the length of theconductor?
  • g
  • c
  • l
  • r
Q24 | The primary parameter that is associated with the magnetic flux linkage is
  • r
  • l
  • c
  • g
Q25 | The primary parameter that is associated with the electric charges is
  • g
  • r
  • c
  • l