RRB JE Stage II : Electrical Engineering Quiz | 21st August

Dear aspirants,

RRB JE Stage II exam is scheduled to be conducted from 28th August to 1st September2019. The overall merit for the selection will be made on the basis of the marks scored in stage II, so candidates need to prepare thoroughly for the second stage. To help the aspirants, Adda247 has come up with a study plan in which we will provide you daily quizzes of all technical subjects. The below quiz will be helpful for the candidates who opted Electrical as the exam group in RRB JE stage II. 

Q1. 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

S1. (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.

Q2. Corona results in
(a) radio interference
(b) power factor improvement
(c) better regulation
(d) none of the above

S2. (a)
Sol.
Corona results in radio interference

Q3. 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

S3. (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.

Q4. 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

S4. (b)
Sol.
The ground ring transmission lines are used to reduce the earth capacitance of the lowest unit

Q5. 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.

Q6. The power factor of the circuit shown in Fig. is ……….

(a) 0.8 lagging
(b) 0.4 lagging
(c) 0.75 lagging
(d) 0.6 lagging

Q7. A moving coil instrument having meter resistance of 5Ω is to be used as a voltmeter of range 0-100 V. If the full-scale deflection current is 10 mA, then required series resistance is………….
(a) 20Ω
(b) 1000Ω
(c) 9995Ω
(d) None of these

Q8. The method of symmetrical components is very useful for
(a) solving unbalanced 3-phase circuits
(b) analyzing the performance of 3-phase electrical machinery
(c) calculating currents resulting from unbalanced faults
(d) all of the above

S8. Ans.(d)
Sol.
The method of symmetrical components is very useful for solving unbalanced 3-phase circuits, analyzing the performance of 3-phase electrical machinery, calculating currents resulting from unbalanced faults.

Q9. Mains a.c. power is converted into d.c. power for……………
(a) lighting purposes
(b) heaters
(c) using in electronics equipment
(d) none of the above

S9. Ans.(c)
Sol. We require d.c. supply for electronic equipment but available supply is a.c. therefore, we use rectifiers to convert a.c. into d.c.

Q10. What happens to the tension in a conductor hanged between two poles, when temperature varies?
(a) Tension increases with increase in temperature
(b) Tension decreases with increase in temperature
(c) Tension first increases and decreases with decrease in temperature
(d) Tension in conductor is independent of temperature variation

S10.Ans(b)
SOL: The relationship between tension and sag is dependent on the loading conditions and temperature variations. For instance, the tension increases when temperature decreases.

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