# SSC JE Electrical Important MCQ Part 2

SSC JE Electrical Important MCQ PDF Part 2

1.Buchholz relay is installed on

A) Oil cooled transformer

B) Welding transformer

C) Furnace transformer

D) Air cooled transformer

2.A 5 kW, 50 Hz, 6-pole slip-ring induction motor runs at 960 RPM. Calculate its synchronous speed and percentage slip.

A) 750 RPM, 2%

B) 900 RPM, 5%

C) 1500 RPM, 4%

D) 1000 RPM, 4%

Answer : D (F=PNs/120 or Ns=120*F/P=120*50/6=1000 RPM,S=(Ns-N)/Ns=(1000-960)/1000=40*100/1000=4%)

3.Which of the following materials is not used as fuse element

A) Aluminium

B) Copper

C) Carbon

D) Silver

4.The ratio of active power to apparent power is known as _________ factor.

B) Power

C) Form

D) Demand

5.EMF equation of a transformer with respect to primary and secondary windings is _______.(where ϕm-flux, f-frequency, N1-number of turns in the primary winding, N2-number of turns in the secondary winding, Bm-flux density)

A) All of these

B) E1 = 4.44 f N1 ɸm

C) E1 = 4.44 f N1 BmAi

D) E2 = 4.44 f N2 ɸm

6.The ratio of the maximum power from the solar cell to the product of short circuit current and open circuit voltage is known as

A) Peak factor

B) Form factor

C) Fill factor

D) RMS

Answer  : C (The Fill Factor (FF) is essentially a measure of quality of the solar cell. It is calculated by comparing the maximum power to the theoretical power that would be output at both the open circuit voltage and short circuit current together.)

7.Which of the following are the advantages of rotating field in large alternators

A) Improved ventilation arrangement

B) Better insulation to armature

C) Ease of construction

D) All of these

8.In AC parallel circuit the angle between voltage and current of each branch will be _________.

A) Cannot say

B) Different

C) Same

D) Zero

9.The value of stacking factor is usually

A) Equal to unity

B) Greater than unity

C) Zero

D) Less than unity

Answer  : D (The stacking factor is the ratio of electrical steel along the axial length of the iron core.The stacking factor is sometimes also called lamination factor or space factor.The value of stacking factor is usually less than unity.)

10.If the equation of sinusoidal current is 141.4 sin 314t. Find the RMS value and frequency of the current.

A) 400 A and 200 Hz

B) 100 A and 50 Hz

C) 300 A and 150 Hz

D) 200 A and 100 Hz

(V=141.4 sin 314t

On complaining with,V=Vm sin 2πft

We get,2πf=314f=314/2π=50Hz

Vm(Peak value)=141.4V

Vrms=Vm/2=141.4V/2=100V)

11.In which of the following is a Britannia Tee joint used

A) Underground cables

B) Power wiring

D) Conduit wiring

Answer : C (The Britannia joint is a form of electrical joint used for bare overhead wires where great tensile strength is required. The two wires are each tinned, and then each have a short shoulder bent in them, and are then bound together with tinned wire before the whole is soldered.)

12.The maximum power transfer theorem can be applied to

A) DC circuits only

B) Neither AC nor DC circuits

C) AC circuits only

D) Both AC and DC circuits

13.Numbers that are written with base 8 are classified as

A) Real numbers

C) Octal numbers

D) Negative numbers

14.The speed of a DC motor is directly proportional to

A) Flux per pole

B) Speed of motor

C) Back EMF

D) Number of armature conductors

(The back emf equation of DC motor is given by

Eb=NPφZ/60A

Here, N = speed of rotation in rpm. P = number of poles. A = number of parallel paths. Z = total no. conductors in armature.

Thus speed N=60AEb/PZφ

N=Eb/kφ where k=PZ/60A is a constant

Hence, speed of a DC motor is directly proportional to emf of rotation (E) and inversely proportional to flux per pole (φ).)

15.In an NPN transistor, P region is called

A) Emitter

B) Base

C) Collector

D) Source

16.Earthing Practice Rule 33 of ____________ makes it compulsory for licensee to maintain a suitable earthed terminal.

A) Indian Electricity Rules 1960

B) Indian Electricity Rules 1956

C) Indian Electricity Rules 1950

D) Indian Electricity Rules 1966

Answer  : B (Earthing Practice Rule 33 of Indian Electricity rules 1956 makes it compulsory for licensee to maintain a suitable earthed terminal in consumer’s premises)

17.Which of the following type of wattmeters is used only on AC

A) Induction type wattmeter

B) Dynamometer type suspended-coil torsion wattmeter

C) Dynamometer type pivoted-coil directreading wattmeter

D) Electrostatic type wattmeter

18.TRS cables on batten are suitable for places

A) Not exposed to sun and rain

B) Exposed to atmosphere

C) Fire hazard is present

D) Where acids and alkalis are present

Answer : A (The disadvantages of batten wiring are Not suitable for outdoor wiring)

19.The PIV rating of 1N4007 rectifier diode is

A) 600 V

B) 1000 V

C) 200 V

D) 400 V

Answer  : B (1N4007 is a rectifier diode, designed specifically for circuits that need to convert alternating current to direct current. It can pass currents of up to 1 A, and have peak inverse voltage (PIV) rating of 1,000 V)

20.Joint box wiring method might be cheaper with respect to

A) Cost wise

B) Power saving

C) Cable length

D) Labour

Answer  : C (Joint Box or Tee or Jointing System-In this method of wiring, connections to appliances are made through joints. These joints are made in joint boxes by means of suitable connectors or joints cutouts. This method of wiring doesn’t consume too much cables size.)