Quiz: Electrical Engineering 26 march 2020

Quiz: Electrical Engineering

Date: 26/03/2020

Exam: UPPSC AE

Topic: Miscellaneous

 

Each question carries 1 mark.

Negative marking: 1/3 mark

Time: 10 Minute

 

Q1. In voltmeter-ammeter method of measuring the value of resistance R. This method is used to measure R if its value is

(a) very low

(b) very high and moderate

(c) cannot say

(d) none of above

L1Difficulty 3

QTags Measurement and measuring instrument

QCreator Devbrat Kumar

 

Q2. In single line diagram of a 3 –phase transmission line. The three phase short-circuit fault (i.e. Symmetrical fault) will be

(a) more severe at

(b) more severe at F2

(c) same severe at F1 and F2

(d) none of the above

L1Difficulty 3

QTags Switchgear and protection

QCreator Devbrat Kumar

 

Q3. A reversed biased p n junction has……….

(a) very narrow depletion layer

(b) almost no current

(c) very low resistance

(d) large current flow

L1Difficulty 3

QTags Semiconductors & diodes

QCreator Devbrat Kumar

 

Q4. Value of the load impedance for which the load consumes maximum power is

(a) 50  at a power factor of 0.6 lead

(b) 50 at a power factor of 0.6 lag

(c) 30  at a power factor of unity

(d) None of the above

L1Difficulty 3

QTags Network theorems

QCreator Devbrat Kumar

 

Q5. A magnet does not attract

(a) cobalt

(b) nickel

(c) copper

(d) iron

L1Difficulty 3

QTags Electrical

QCreator Devbrat Kumar

 

Q6. Owing to skin effect

(a) current flows through the half cross-section of the conductor

(b) portion of the conductor near the surface carries more current and core of the conductor carries less current

(c) portion of the conductor near the surface carries less current and core of the conductor carries more current

(d) any of the above

L1Difficulty 3

QTags Power generation, transmission and distribution

QCreator Devbrat Kumar

 

Q7. Corona results in

(a) radio interference

(b) power factor improvement

(c) better regulation

(d) none of the above

L1Difficulty 3

QTags Power generation, transmission and distribution

QCreator Devbrat Kumar

 

Q8. When the load at the receiving end of a long transmission line is removed, the sending

end voltage is less than the receiving end voltage. This effect is known as

(a) Ferranti effect

(b) Proximity effect

(c) Kelvin effect

(d) Faraday effect

L1Difficulty 3

QTags Power generation, transmission and distribution

QCreator Devbrat Kumar

 

Q9. The ground ring transmission lines are used to

(a) reduce the transmission losses

(b) reduce the earth capacitance of the lowest unit

(c) increase the earth capacitance of the lowest unit

(d) None of the above

L1Difficulty 3

QTags Power generation, transmission and distribution

QCreator Devbrat Kumar

 

Q10. As the power factor of a circuit is increased, ………….

(a) reactive power is decreased

(b) active power is decreased

(c) reactive power is increased

(d) both active and reactive powers are increased.

L1Difficulty 3

QTags Network & Circuit Theory

QCreator Devbrat Kumar

 

Solutions

 

S1. Ans.(b)

Sol. Let voltmeter read V and ammeter read I. then,

V = IRa+ IR or R = V/I – Ra

Since R is high, the value of Ra can be neglected.

 

S2. Ans.(a)

Sol. Because impedance of the network up to point F1 will be less than up to

 

S3. Ans.(b)

Sol. A reversed biased pn junction has almost no current.

S4. Ans.(b)

S5. Ans.(c)

Sol. Copper is a diamagnetic material and hence, it is not attracted by magnets.

S6. Ans.(b)

Sol. The phenomena arising due to unequal distribution of current over the entire cross section of the conductor being used for long distance power transmission is referred as the skin effect in transmission lines. Such a phenomenon does not have much role to play in case of a very short line, but with increase in the effective length of the conductors, skin effect increases considerably. So, the modifications in line calculation needs to be done accordingly.

The distribution of current over the entire cross-section of the conductor is quite uniform in case of a DC system. But what we are using in the present era of power system engineering is predominantly an alternating current system, where the current tends to flow with higher density through the surface of the conductors.

S7. Ans.(a)

Sol. Corona results in radio interference

S8. Ans.(a)

Sol. The effect in which the voltage at the receiving end of the transmission line is more than the sending voltage is known as the Ferranti effect. Such type of effect mainly occurs because of light load or open circuit at the receiving end.

S9. Ans.(b)

Sol. The ground ring transmission lines are used to reduce the earth capacitance of the lowest unit.

S10. Ans.(a)

Sol.  Power factor =

So, the power factor of a circuit is increased, reactive power is decreased.

 

 

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