Quiz: Electrical Engineering 7 April 2020

Quiz: Electrical Engineering

Exam: UPSSSC JE

Topic: Miscellaneous

 

Each question carries 1 mark.

Negative marking: 1/4 mark

Time: 10 Minute

 

 

 

Q1. Resistance of an ammeter having range 0–5A is 1.8 Ω. It is shunted by a resistor of 0.2 Ω. What is the effective current when the pointer reads 2 A?

(a) 10 A

(b) 30 A

(c) 15 A

(d) 20 A

L1Difficulty 2

QTags Measurement and measuring instrument

QCreator Balwant Kumar

 

 

Q2. The overall efficiency of a steam power station is ………. its thermal efficiency.

(a) less than

(b) more than

(c) equal to

(d) none of the above

L1Difficulty 1

QTags Power generation, transmission and distribution

QCreator Balwant Kumar

 

 

Q3. In a power station,

(a) Reserve capacity = Plant capacity + Max. demand

(b) Reserve capacity = Plant capacity – Average demand

(c) Reserve capacity = Plant capacity – Max. demand

(d) Reserve capacity = Plant capacity + Average demand

L1Difficulty 1

QTags Power generation, transmission and distribution

QCreator Balwant Kumar

 

 

Q4. In a 3-phase system, the line losses are

(a) directly proportional to cos ϕ

(b) inversely proportional to cos ϕ

(c) inversely proportional to cos² ϕ

(d) none of the above

L1Difficulty 1

QTags Power generation, transmission and distribution

QCreator Balwant Kumar

 

 

Q5. Superposition theorem is essentially based on the concept of

(a) Reciprocity

(b) Linearity

(c) Duality

(d) Non-linearity

L1Difficulty 1

QTags Network theorems

QCreator Balwant Kumar

 

 

Q6. One coulomb of electrical charge is contributed by how many electrons?

(a) 0.625×10^19
(b) 1.6×10^19
(c) 10^19
(d) None of these

L1Difficulty 1

QTags Basic electrical engineering

QCreator Balwant Kumar

 

 

Q7. A current is said to be alternating when it changes in:

(a) Magnitude

(b) Direction

(c) Both magnitude and direction

(d) None of these

L1Difficulty 1

QTags AC fundamentals

QCreator Balwant Kumar

 

 

Q8. Voltage applied across a ceramic dielectric produces an electrostatic field 100 times greater than in air. The dielectric constant of the ceramic equals_________.

(a) 100/3

(b) 50

(c) 100

(d)  1/100

L1Difficulty 1

QTags Switchgear and protection

QCreator Balwant Kumar

 

 

Q9. Internal heating of capacitor is usually attributed to_________.

(a) dielectric charge

(b) plate vibration

(c) electron movement

(d) leakage resistance

L1Difficulty 2

QTags Basic electrical engineering

QCreator Balwant Kumar

 

 

Q10.In a parallel circuit operating with a source of 30 V AC, designed to carry a total current of 6 A, what happens to the protection device (fuse) when the resistance suddenly changes to 2Ω?

(a) It closes

(b) There is no change

(c) It shorts to ground

(d) It opens

L1Difficulty 1

QTags AC fundamentals

QCreator Balwant Kumar

 

 

 

 

Solution

 

S1.(D)

Sol. Multiplying power of shunt, n=(G+S)/S=G/S+1=1.8/0.2+1=10

Therefore, the range of ammeter increases 10 times. When the ammeter indicates 2 A, the circuit current = 2 ×10 = 20 A.

S2.(A)

Sol. The overall efficiency of a steam power station is less than its thermal efficiency. This is expected since some losses (about 1%) occur in the alternator.

 

S3.(C)

 

S4.(C)

Sol. Line current,

Since line losses are proportional to the square of , it follows that line losses are proportional to 1/cos² ϕ

 

 

S5. (b) Superposition theorem is used in the linear circuits having more than one independent voltage or current sources.

 

S6. Ans.(a)

Sol.   One coulomb has 0.625 × 1019 electron

 

S7. Ans.(c)

Sol.

A current is said to be alternating when it changes in both magnitude and direction

S8. (c)

Electric field due to ceramic dielectric = k  ; V = Applied voltage

∴ E ∝ k If  = constant                                    K = Dielectric constant

For air K = 1

∴                ⇒

= Dielectric constant for ceramic

S9. (d)

Leakage resistance

S10. (d)

Initial resistance of circuit =  = 5 Ω

Rated current = 6A

Now,

Here, I >  ⇒ Fuse opens

 

 

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