Top 250+ Solved Electromagnetic Theory MCQ Questions Answer

From 16 to 30 of 292

Q. Which of the following statements is correct ?

a. Air capacitors have a blackband to indicate the outside foil

b. Electrolytic capacitor must be con¬nected in the correct polarity

c. Ceramic capacitors must be con¬nected in the correct polarity

d. Mica capacitors are available in capacitance value of 1 to 10 pF

  • b. Electrolytic capacitor must be con¬nected in the correct polarity

Q. The dissipation factor of a good dielectric is of the order of

a. 0.0002

b. 0.002

c. 0.02

d. 0.2

  • a. 0.0002

Q. "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

  • b. Gauss's law

Q. 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

  • c. two in parallel and third in series with this combination

Q. For which of the following parameter variation, the capacitance of the capacitorremains unaffected ?

a. Distance between plates

b. Area of the plates

c. Nature of dielectric

d. Thickness of the plates

  • d. Thickness of the plates

Q. Point out the wrong statement.Magnetic leakage is undesirable in electric machines because it

a. lowers their power efficiency

b. increases their cost of manufacture

c. leads to their increased weight

d. produces fringing

  • a. lowers their power efficiency

Q. Relative permeability of vacuum is

a. 1

b. 1 H/m

c. 1/4JI

d. 4n x 10-' H/m

Q. Permanent magnets are normally made of

a. alnico alloys

b. aluminium

c. cast iron

d. wrought iron

  • a. alnico alloys

Q. The rate of rise of current through an inductive coil is maximum

a. at 63.2% of its maximum steady value

b. at the start of the current flow

c. after one time constant

d. near the final maximum value of current

  • b. at the start of the current flow

Q. When both the inductance and resistance of a coil are doubled the value of

a. time constant remains unchanged

b. initial rate of rise of current is doubled

c. final steady current is doubled

d. time constant is halved

  • a. time constant remains unchanged

Q. A material for good magnetic memory should have

a. low hysteresis loss

b. high permeability

c. low retentivity

d. high retentivity

  • d. high retentivity
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