DSSSB JE Electrical Previous Year Question Papers| 5 November 2019 Paper

Question 01: In a circuit shown below the voltage across 100 ohm resistance is

A. 50 V
B. 100 V
C. 60 V
D. 120 V

Answer: 120V

Question 02: Current in Ampere in an inductor is given by 10 + 10 t where t is the time in seconds. If the self- induced emf in the coil is 20 mV, then its self-inductance is:

A. 10 mH
B. 1 mH
C. 2 mH
D. 20 mH

Answer: 2mH

Question 03: Equivalent resistance of the circuit shown below between X and Y

A. 6 ohm
B. 9 ohm
C. 18 ohm
D. 12 ohm

Answer: 9 ohm

Question 04: Equivalent resistance seen between the terminal a and b for the circuit shown below is:

A. 20 ohm
B. 4 ohm
C. 25 ohm
D. 5 ohm

Answer: 4 ohm

Question 05: Reciprocal of reluctance is

A. Reluctivity
B. Permeance
C. Permeability
D. Susceptibility

Answer: Permeance

Question 06: An average voltage of 40 V is induced in a 1000 turn coil due to a change in flux which occurs in 0.5 seconds. The total flux change in webers is

A. 0.02
B. 0.05
C. 0.01
D. 0.04

Answer: 0.02

Question 07: Two filament lamps rated 200 W/200 V and 50 W/200 V are connected in series across a 200 V, 50 Hz, ac supply. Then, the total power supplied by the source is:

A. 160 W
B. 80 W
C. 20 W
D. 40 W

Answer: 40W

Question 08: A battery having an open circuit voltage of 2 V has a terminal voltage of 1 V when supplying a current of 5 A. Its internal resistance is

A. 0.60
B. 0.40
C. 0.2 0
D. 0.1 0

Answer: 0.2 0

Question 09: An iron cored choke coil has an equivalent resistance of 4 0. It draws 10fi from a single phase ac source of voltage 200 V, 50 Hz. Then, power consumed by the coil and its power factor respectively are:

A. 200 W, 0.2 lag
B. 400 W, 0.2 lag
C. 200 W, 0.2 lead
D. 400 W, 0.2 lead

Answer: 400 W, 0.2 lag

Question 10: Mutual inductance between two closely coupled coils is 2 H. Now, if the number of turns in one coil is reduced by 50 percent and those of the other coil is doubled then, new value of mutual inductance is:

A. 2 H
B. 8 H
C. 1 H
D. 4 H

Answer: 2 H

Question 11: In the circuit below, the value of resistance R is

A. 20 ohm
B. 30 ohm
C. 10 ohm
D. 40 ohm

Answer: 20 ohm

Question 12: A conductor 0.2 m long is carrying a current of 20 A at right angles to a magnetic field of 0.5 Tesla. What will be force on the conductor of the current is increased by 50 percent?

A. 1 N
B. 4 N
C. 6 N
D. 3 N

Answer: 3 N

Question 13: When applied with a unidirectional voltage, an inductor behaves virtually like a

A. Depends on the magnitude of voltage applied
B. Short circuit
C. Depends on the polarity of voltage applied
D. open circuit

Answer: Short circuit

Question 14: A non-ideal current source of 25 mA is supplying a resistive load of 5 kO. If the actual current flowing through the load is 20 mA, then the internal resistance of the source is:

A. 1 K ohm
B. 10 K ohm
C. 5 K ohm
D. 20 K ohm

Answer: 20 K ohm

Question 15: Three resistances are connected in parallel. Total circuit current is 6 A. Individual conductance of each parallel circuit are G1 = 1 S, G2 = 3 S, and G3 = 2 S. Then, current through G3 is:

A. 4 A
B. 1 A
C. 6 A
D. 2 A

Answer: 2 A

Question 16: In the circuit shown below, the current drawn by the 6 0 resistor is 2 A. then the value of resistance R is

A. 9 ohm
B. 18 ohm
C. 3 ohm
D. 6 ohm

Answer: 9 ohm

Question 17:Find Va – Vb in the following part of a closed circuit where Va and Vb are the potentials at a and b.

A. 10 V
B. 15 V
C. 5 V
D. 20 V

Answer: 10 V

Question 18: Certain number of resistors having equal resistances offers an equivalent resistance of 1 0 when connected in parallel and 100 0 if they are connected in series. Then, the number of resistors and the resistance of each are

A. 20, 10 ohm
B. 5, 20 ohm
C. 20, 5 ohm
D. 10, 10 ohm

Answer: . 10, 10 ohm

Question 19: The RMS value of a half-wave rectified symmetrical square wave current of 2 A is

A. √2 A
B. 1 A
C. 1/ √2 A
D. √3 A

Answer: √2 A

Question 20: In a given circuit, the voltage across 9 ohm resister is

A. 54 v
B. 50 v
C. 75 v
D. 45 v

Answer: 45 V

Question 21: In a synchronous generator supplying power at rated voltage with zero power factor lagging, the effect of armature reaction ampere turns is:

A. Demagnetizing
B. Cross magnetizing
C. Magnetizing
D. Magnetizing and cross magnetizing

Answer: Demagnetizing

Question 22: Field system of an alternator is usually excited from:

A. Single phase ac voltage
B. Square wave voltage
C. Three phase ac voltage
D. DC voltage

Answer: DC voltage

Question 23: Scott connected transformers can convert

(a) three-phase to two-phase
(b) two-phase to three-phase
(c) two-phase to four-phase
(d) three-phase to four-phase.

From the above options correct answer is:

A. a and c
B. b and c
C. b and d
D. a and b

Answer: a and b

Question 24: Torque developed by a motor while running at 1000 rpm is 106 N-m and the shaft torque available is 100 N-m. thesn the iron and mechanical losses in watts are:

A. 300 π
B. 50 π
C. 200 π
D. 100 π

Answer: 200 π

Question 25:In a low power factor wattmeter compensating coil is connected:

A. In series with the current coil
B. In series with the pressure coil
C. In parallel with the pressure coil
D. In parallel with the current coil

Answer: In series with the pressure coil

Question 26: Loss of charge method is used for the measurement of:

A. High inductance
B. Low resistance
C. Low inductance
D. High resistance

Answer: High resistance

Question 27: During plugging of a three-phase induction motor:

A. Rotor circuit is opened
B. Phase sequence of the stator voltage is reversed
C. One phase of stator is short circuited
D. Dc source is connected to stator

Answer: Phase sequence of the stator voltage is reversed

Question 28: A transformer is supplying a unity power factor load. Power factor on primary side will be

A. About 0.95 lag
B. unity
C. About 0.95 lead
D. zero

Answer: About 0.95 lag

Question 29: A dc shunt generator has a critical field resistance of 400 0 at 1200 rpm. Now if the speed of the generator is increased to 1800 rpm what is the change in the critical resistance?

A. Increases to 900 ohm
b. Remains the same
c. Increases to 600 ohm
d. Decreases to 267 ohm

Answer: Increases to 600 ohm

Question 30: A three phase star connected alternator develops an rms voltage of V1 per phase at the fundamental frequency. It also generates a third harmonic component whose rms value is V3 . What is the line voltage of the alternator?


Question 31: In hydro-electric plants the type of alternator used is:

A. Turbo generator
B. Non salient pole
C. Salient pole
D. Steam turbine generator

Answer: Salient pole

Question 32: A current transformer has a phase error of +5 degree. The phase angle between the primary and secondary current is:

A. 5 degree
B. 95 degree
C. 175 degree
D. 85 degree

Answer: 175 degree

Question 33: Ferranti effect on long overhead lines is experienced when:

A. Power factor is unity
B. Line is lightly loaded
C. Line is heavily loaded
D. Line is fully loaded

Answer: Line is lightly loaded

Question 34: A 400 V three phase 50 Hz balanced source is supplying power to a balanced three phase load. Line current flowing through the load is 5A at a power factor angle of 30 degrees lagging. Reading of two wattmeters used to measure the load power are:

A. 1000 W, 2000 W
B. 2000 W, 4000 W
C. 2000 W, 3000 W
D. 1000 W, 3000 W

Answer: 1000 W, 2000 W

Question 35: An industrial consumer has a load pattern of 2000 kW at 0.8 lagging for 12 hours and 1000 kW at unity power factor for 12 hours. Its load factor is

A. 0.6
B. 0.8
C. 0.5
D. 0.75

Answer: 0.75

Question 36: Current flowing in a circuit is i = (18 + 10sinωt + 7sin2ωt). A moving iron ammeter is connected in the circuit to measure this current. The reading of the meter will be approximately:

A. 28 A
B. 35 A
C. 18 A
D. 20 A

Answer: 20 A

Question 37: Moving-coil permanent magnet instruments can be used for the measurement of

A. AC and DC
B. AC only
C. DC only
D. half-wave rectified DC

Answer: DC only

Question 38:Form factor of sinusoidal AC signal is

A. 1.11
B. 0.11
C. 2.11
D. 3.11

Answer: 1.11

Question 39: Voltage applied to a load is 100√2 sin500t. Current through the load is 10√2 sin(500t + π/3). The power consumed by the load is:

A. 500 W
B. 200 W
C. 1000 W
D. 2000 W

Answer: 500 W

Question 40: A three-phase induction motor is running at 5 percent slip with certain load. If at this load the power input to the rotor is 2000 W, then the mechanical power developed by the motor is:

A. 2000 W
B. 2100 W
C. 1700 W
D. 1900 W

Answer: 1900 W

Question 41: In a particular circuit, a coil having a self- inductance of 2 H is required to carry a current of 4 A. A capacitor rated for 400 V is used across the coil in order to prevent sparking during breaking of the circuit. The value of capacitor needed is:

A. 120 µF
B. 100 µF
C. 400 µF
D. 200 µF

Answer: 200 µF

Question 42: unite of reluctance is:

A. Henry
B. Weber
C. Weber/m2
D. (Henry)-1

Answer: (Henry)-1

Question 43: In a transmission system if V is the transmission voltage, weight of copper needed is proportional to:

A. V

B. 1/V2

C. V2

D. 1/V

Answer: 1/V2

Question 44: Cost of power generation will be low if:

A. Load factor is low and diversity factor is high
B. Load factor is high and diversity factors is low
C. Load factor and diversity factor are low
D. Load factor and diversity factor are high

Answer: Load factor and diversity factor are high

Question 45: Energy produced in a power station is 1440 MWh per day. What is the maximum demand of the station if its load factor is 0.5?

A. 120 MW
B. 280 MW
C. 60 MW
D. 140 MW

Answer: 120 MW

Question 46: Sag of the conductors of a transmission line is 2 m when the span is 200 m. Now if the height of the supporting tower is increased by 25 percent sag will

A. Increase by 25 percent
B. Reduce by 25 percent
C. Reduce by 12.5 percent
D. Remains unchanged

Answer: Remains unchanged

Question 47: A motor has to be selected for following load cycle. Load uniformly rising from zero to 100 hp in 10 minutes after which it is constant at 100 hp for the next 10 minutes, followed by no load period of 30 minutes. Suitable size of continuous rated motor is:

A. 100 hp
B. 25 hp
C. 50 hp
D. 200 hp

Answer: 50 hp

Question 48: In dielectric heating, the current flows through:

A. Air
B. Dielectric
C. Metallic conductor
D. The ionic discharge between dielectric medium and metallic conductor

Answer: Dielectric

Question 49: Gain of a buffer amplifier is:

A. Dependent on the circuit parameters
B. Unity
C. infinity
D. zero

Answer: Unity

Question 50: The most economical method of electrical braking is:

A. Plugging
B. Dynamic braking with self-excitation
C. Regenerative braking
D. Dynamic braking with separate excitation

Answer: Regenerative braking