Quiz: Electrical Engineering 11 April 2020

Quiz: Electrical Engineering
Exam: UPPSC-AE
Topic: Miscellaneous

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

Q1. Kirchhoff’s voltage law deals with
(a) conservation of energy
(b) conservation of charge
(c) conservation of momentum
(d) conservation of angular momentum
L1Difficulty 1
QTags Network theorems
QCreator Balwant Kumar

Q2. Two bulbs rated at 25 W, 110 V and 100 W, 110 V are connected in series to a 220 V supply. What will happen to the circuit?
(a) 100 W bulb will burn out
(b) 25 W bulb will burn out
(c) both bulbs will burn out
(d) no bulb will burn out
L1Difficulty 2
QTags Network theorems
QCreator Balwant Kumar

Q3. An ammeter has a resistance of 50 Ω and requires 10 mA for full-scale deflection. The shunt resistance S required to allow the meter to measure currents up to 100 mA is
(a) 5.56 Ω
(b) 2.5 Ω
(c) 15.75 Ω
(d) 8.75 Ω
L1Difficulty 1
QTags Measurement and measuring instrument
QCreator Balwant Kumar

Q4. For transfer of maximum power, the relation between load resistance RL and internal resistance ri of the voltage source is ……….
(a) RL=2 Ri
(b) RL =0.5 Ri
(c) RL =1.5 Ri
(d) RL =Ri
L1Difficulty 2
QTags Network theorems
QCreator Balwant Kumar

Q5. A 16 mA current source has an internal resistance of 10 kΩ . How much current will flow in a 2.5 kΩ load connected across its terminals?
(a) 4.2 mA
(b) 6 mA
(c) 11.5 mA
(d) 12.8 mA
L1Difficulty 3
QTags Network theorems
QCreator Balwant Kumar

Q6. Two resistors of resistances 8 Ω and 12 Ω are connected in parallel. The power dissipated in 8 Ω resistor is 9 W. The power dissipated is 12 Ω resistor is
(a) 12 W
(b) 24 W
(c) 6 W
(d) 16 W
L1Difficulty 3
QTags Network & Circuit Theory
QCreator Balwant Kumar

Q7. What is the coupling field used between the electrical and mechanical systems in an energy conversion device?
a) Magnetic field
b) Electric field
c) Magnetic field or Electric field
d) None of the mentioned
L1Difficulty 3
QTags Network & Circuit Theory
QCreator Balwant Kumar

Q8. What is the angle between stator direct axis and quadrature axis of a reluctance motor?
a) 90°
b) 0°
c) 45°
d) any of the mentioned
L1Difficulty 3
QTags Alternators
QCreator Balwant Kumar

Q9. The variation of reluctance RL with space angle θr depends on the shape of __________
a) stator poles
b) rotor poles
c) stator or rotor poles
d) both stator and rotor poles
L1Difficulty 3
QTags Alternators
QCreator Balwant Kumar

Q10. Reluctance motor can produce torque at ________
a) any speed less than synchronous speed
b) synchronous speed only
c) any speed greater than synchronous speed
d) any of the mentioned
L1Difficulty 3
QTags Alternators
QCreator Balwant Kumar

Solution
S1. (a)
∑▒〖V=W〗 = Total energy

S2. (b)
Current flowing through the circuit is more than the rated current of 25 W, 110 V bulb.

S3. (a)
Full-scale voltage across meter = IR=10 mA×50 Ω=0.5 V. When circuit current is 100 mA, current through shunt = 100 – 10 = 90 mA.
∴ S=(0.5 V)/(90 mA)=5.56 Ω

S4. (d)

S5. (d)
Fig. below shows the conditions of the problem. The current source provides 16 mA to two parallel connected resistors. Therefore, current in 2.5 kΩ load is
I_2=16×10/(10+2.5)=16×10/12.5=12.8 mA
S6. (c)
P=V^2/R or V=√(PR.) Since voltage is same in a parallel circuit, P_1 R_1=P_2 R_2 or 9×8 = P_2×12
∴P_2=6 W
S7. (c)
Explanation: Either electric field or magnetic field can be used, however most commonly we use magnetic field because of its greater energy storage capacity.

S8. (a)
Explanation: In reluctance motor, direct axis is horizontal axis and quadrature axis is at 90° to the direct axis.

S9. (d)
Explanation: Also, the variation is assumed to be a function of space angle θr.

S10.( b)
Explanation: Te(av)=-1/4 ∅_max^2 (R_lq – R_ld)(1/2 sin⁡(-2δ)), w= synchronous speed
if wr≠w then Te(av)=0 ,and if wr = w then Te(av) ≠ 0, as the last term in the equation 1/2 sin(-2δ) does not vary with time, and hence average torque is not equal to zero.

 

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