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Electrostatics

Study 180 Electrical Engineering MCQs with correct answers and explanations.

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171Electrical EngineeringMedium

A capacitor having capacitance of 5 uF is charged to a potential difference of 10,000 V. The energy stored in the capacitor is________?

A200 joules

B50 joules

C150 joules

D250 joules

Correct answer

D. 250 joules

Explanation

The correct answer is 250 joules.

172Electrical EngineeringMedium

The time constant of an R-C circuit is defined as the time during which capacitor charging voltage actually rises to ________ percent of its value

A37, initial

B62, final

C62, initial

D37, final

Correct answer

B. 62, final

Explanation

The correct answer is 62, final.

173Electrical EngineeringMedium

A potential of 400 V is applied to a capacitor, the plates of which are 4 mm apart. The strength of electric field is________?

A10 kV/m

B2 kV/m

C5 kV/m

D100 kV/m

Correct answer

D. 100 kV/m

Explanation

The correct answer is 100 kV/m.

174Electrical EngineeringMedium

Mica capacitors are characterized by all of the following except________?

Aaccurate value

Blow losses

Cstable operation

Dlow leakage reactance

Correct answer

D. low leakage reactance

Explanation

The correct answer is low leakage reactance.

175Electrical EngineeringMedium

The potential gradient across the material of low permittivity is than across the material of high permittivity?

Aboth (A) and (B)

Bsmaller

Cnone of the above

Dgreater

Correct answer

D. greater

Explanation

The correct answer is greater.

176Electrical EngineeringMedium

When a dielectric is placed in an electric field the field strength________?

Areduces to zero

Bincreases

Cdecreases

Dremain unchanged

Correct answer

C. decreases

Explanation

The correct answer is decreases.

177Electrical EngineeringMedium

For making a capacitor, it is better to select a dielectric having________?

Ahigh permittivity

Bpermittivity same as that of air

Clow permittivity

Dpermittivity slightly more than that of air

Correct answer

A. high permittivity

Explanation

The correct answer is high permittivity.

178Electrical EngineeringMedium

In a capacitive circuit________?

Aan increase in applied voltage makes a capacitor charge

Bnone of the above

Ca steady value of applied voltage causes discharge

Ddecrease in applied voltage makes a capacitor charge

Correct answer

A. an increase in applied voltage makes a capacitor charge

Explanation

The correct answer is an increase in applied voltage makes a capacitor charge.

179Electrical EngineeringMedium

A single core cable used on 33000 V has conductor diameter 10 mm and the internal diameter of sheath 25 mm. The maximum electrostatic stress in the cable is________?

A62 x 105 V/m

B92 x 105 V/m

C72 x 105 V/m

D82 x 105 V/m

Correct answer

C. 72 x 105 V/m

Explanation

The correct answer is 72 x 105 V/m.

180Electrical EngineeringMedium

Permittivity is expressed in________?

AFarad/meter

BWeber/meter

CFarad/sq-m

DWeber/sq-m

Correct answer

A. Farad/meter

Explanation

The correct answer is Farad/meter.

In a capacitive circuit________?

Aan increase in applied voltage makes a capacitor charge

Bnone of the above

Ca steady value of applied voltage causes discharge

Ddecrease in applied voltage makes a capacitor charge

Correct answer

A. an increase in applied voltage makes a capacitor charge

Explanation

The correct answer is an increase in applied voltage makes a capacitor charge.