Quiz: Electrical Engineering 24 march 2020

Quiz: Electrical Engineering

Exam: UPSSSC JE

Topic: Miscellaneous

 

Each question carries 1 mark.

Negative marking: 1/4 mark

Time: 10 Minute

 

Q1. A voltage source has a terminal voltage of 28 V when its terminals are open-circuited. When a 12Ω load is connected across the terminals, the terminal voltage drops to 24 V. What is the internal resistance of the source?

(a) 0.5 Ω

(b) 1 Ω

(c) 2 Ω

(d) 2.5 Ω

L1Difficulty 3

QTags Network theorems

Qcreator Balwant Kumar

 

Q2. The current through a branch in a linear circuit is 2A when the input source voltage is 10V. If the voltage is reduced to 1V and the polarity is reversed, the current through the branch is

(a) –0.2 A

(b) 0.2 A

(c) 2 A

(d) –2 A

L1Difficulty 3

QTags Network theorems

Qcreator Balwant Kumar

 

 

Q3. One kilowatt hour is equal to

(a) 36 ×  J

(b) 10³ J

(c) 36 × 10⁵

(d) 10⁵

L1Difficulty 1

QTags Utilization of electrical energy

Qcreator Balwant Kumar

 

Q4. You are given resistance wire of length 50 cm and a battery of negligible internal resistance. In which case the maximum amount of heat is generated?

(a) When the wires connected directly across the battery

(b) When the wire is divided into two equal parts and both parts are connected in parallel across the battery

(c) When the wire is divided into four equal parts and all the four parts are connected in parallel across the battery

(d) When only one-half of the wire is connected across the battery

L1Difficulty 1

QTags Utilization of electrical energy

Qcreator Balwant Kumar

 

Q5. Magnetic field inside a current carrying solenoid is

(a) directly proportional to current

(b) directly proportional to its length

(c) inversely proportional to number of turns

(d) inversely proportional to current.

L1Difficulty 3

QTags Magnetic circuit

Qcreator Balwant Kumar

 

Q6. Hysteresis loss can be reduced by ……….

(a) laminating the magnetic circuit

(b) using material of narrow hysteresis loop

(c) increasing m.m.f. of the circuit

(d) none of the above

L1Difficulty 2

QTags Transformer

Qcreator Balwant Kumar

 

Q7. Fringing effect is ignored in a magnetic circuit if air-gap is

(a) large

(b) small

(c) very large

(d) none of the above

L1Difficulty 3

QTags Transformer

Qcreator Balwant Kumar

 

Q8. The nature of armature winding of a d.c. machine is decided by ………

(a) front pitch

(b) commutator pitch

(c) back pitch

(d) none of the above

L1Difficulty 3

QTags DC Motor

Qcreator Balwant Kumar

 

Q9. A triplex wave winding will have …….. parallel paths.

(a) 6

(b) 2

(c) 4

(d) none of the above

L1Difficulty 3

QTags Alternators

Qcreator Balwant Kumar

 

Q10. A shunt generator delivers 195 A at a terminal voltage of 250 V. The armature resistance and shunt field resistance are 0.02Ω and 50Ω respectively. The iron and friction losses equal 950 W. What are the stray losses

(a) 950 W

(b) 3000 W

(c) 1250 W

(d) 1750 W

L1Difficulty 1

QTags 3-Phase induction motor

Qcreator Balwant Kumar

 

 

Solution

S1. Ans.(c)

Sol.

 

S2. Ans.(a)

Sol.

 

S3. Ans.(c)

Sol.

 

S4. Ans.(c)

Sol.

S5. Ans.(a)

Sol.

 

S6. Ans.(b)

Sol.

 

S7. Ans.(b)

Sol.

 

S8. Ans.(b)

Sol. It is the commutator pitch the determines the grouping to coils in series and parallel. In other works, it is the commutator pitch that determines as to how many parallel paths, each consisting of equal number of coils in series, will be formed. Hence, the nature of winding is determined by the Commutator pitch

 

S9. Ans.(a)

Sol. With an n-plex wave winding, the number of parallel paths is 2nwhere n = 2, 3 etc. and stands for duplex, triplex etc.

Hence, a triplex wave winding will have 2 × 3 = 6 parallel paths

 

S10. Ans.(a)

Sol. Usually magnetic and mechanical losses are collectively called stray losses.

 

 

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