Quiz: Electrical Engineering 10 Sep 2020

Quiz: Electrical Engineering
Topic: Miscellaneous

Each question carries 1 mark.
Negative marking: 1/4 mark
Time: 10 Minute

Q1. In the circuit shown below, the voltage and current sources are ideal. The voltage (Vout) across the current source, in volts, is

(a) 0
(b) 5
(c) 10
(d) 20

Q2. The average power delivered to an impedance (4 – j3) Ω by a current 5cos (100πt +100) A is
(a) 42.5 W
(b) 50 W
(c) 62.5 W
(d) 125 W

Q3. The input voltage given to a converter is

The current drawn by the converter is

The input power factor of the converter is
(a) 0.31
(b) 0.44
(c) 0.50
(d) 0.71

Q4. The current through the 2 kΩ resistance in the circuit shown is

(a) 0 mA
(b) 1 mA
(c) 2 mA
(d) 6 mA

Q5. Which of the following statement is true?
(a) At higher voltage, cost of transmission is reduced
(b) At higher voltage, cost of transmission is increased
(c) Both a and b
(d) None of the above

Q6. Gate circuit or triggering circuit of a thyristor is
(a) Magnetic circuit
(b) Low power circuit
(c) High power circuit
(d) May be low power or high-power circuit

Q7. Inside a hollow conducting sphere:
(a) Electric field changes with distance from the Centre of the sphere
(b) Electric field changes with magnitude of charge given to the conductor.
(c) Electric field is a non-zero constant
(d) Electric field is zero

Q8. Maximum number of I/O that can be address by INTEL 8085 is
(a) 512
(b) 256
(c) 1024
(d) 285

Q9. In capacitor start, single phase induction motor, the current in the
(a) supply lines lead the voltage
(b) starting winding lags the voltage
(c) main winding leads the voltage
(d) starting winding leads the voltage

Q10. In a single-phase induction motor, speed sensitive centrifugal switch is connected in________________ winding.
(a) parallel with main
(b) series with main
(c) parallel with starting
(d) series with starting

S1. Ans.(d)

S2. Ans.(b)
Sol. Given that, Z=4-j3=RL-jXc;RL=4 Ω and IL=5cos (100πt +100) A
∴P=1/2 Im^2 RL=1/2×25×4=50 W

S3. Ans.(c)
Sol. input power factor depends on fundamental components.

∴power factor= cos 𝟇=cos (π/3) =0.5

S4. Ans.(a)
Sol. it is a balanced wheat stone bridge.

S5. Ans.(a)
Sol. At higher voltage, volume of conductor is reduced. Area of conductor A ∝ 1/Vs² Where Vs = Supply voltage So that material requirement is reduced and hence cost of the material and transmission is reduced.

S6. Ans.(b)
Sol. Thyristor circuit is high power circuit. But its triggering circuit is low power circuit.

S7. Ans.(d)
Sol. For any conducting sphere, the charge enclosed is zero and hence, the electric field inside it is zero. This is an application of the Gauss Law. In fact, Gaussian surface includes no charges inside it.

S8. Ans.(b)
Sol. I/O has 8- bit port address. So, maximum number of I/O port that can be address by INTEL 8085 is 2^8=256.

S9. Ans.(d)
Sol. In capacitor start induction motor, we are using two winding, the main winding and the starting winding. With starting winding, we connect a capacitor so the current flowing in the capacitor i.e. Ist leads the applied voltage by some angle, φst.

S10. Ans.(d)
Sol. In a single-phase induction motor, speed sensitive centrifugal switch is connected in series with starting winding.
In case of capacitor start induction motor, the centrifugal switch is provided so as to disconnect the starting winding when the motor attains a speed up to 75 to 80% of the synchronous speed.


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