11. Calculate the active power in a 56 μF capacitor if the VRF value is 5.1%.
A. 6 W
B. 0 W
C. 9 W
D. 2 W
Answer: B
The capacitor is a linear element. It only absorbs reactive power and stores it in the form of oscillating energy. The voltage and current are 90° in phase in the case of the capacitor so the angle between V & I is 90°.
P = VIcos90° = 0 W.
12. Calculate the apparent power using the data: P=3 W, Q=4 VAR.
A. 5 VA
B. 6 VA
C. 9 VA
D. 2 VA
Answer: A
The apparent power is the product of the voltage and current conjugate phasor. The value of apparent power is (9+16).5 = 5 VA.
13. Calculate the value of impedance using the data: R=2 Ω, XL=4 Ω.
A. 5.5 Ω
B. 5.4 Ω
C. 2.5 Ω
D. 4.4 Ω
Answer: D
The value of impedance is
{(R)2+(XL)2).5 = (4+16).5 = 4.4 Ω.
It is the total impedance offered by an AC circuit. It is expressed in Ω.
14. Which type of grounding is used to suppress the capacitive effect?
A. Solid grounding
B. Reactance grounding
C. Resistance grounding
D. Peterson coil
Answer: D
Peterson coil or resonance grounding is used to suppress the capacitive effect. The frequency in resonance grounding is ω2 = 1÷(3LC)
15. Electric trains are of two types.
A. True
B. False
Answer: A
Mainline trains and suburban trains are the two types of trains. They run on fixed rails. They are powered by electricity.
16. The shape of pantograph collector is _________________
A. Square
B. Pentagon
C. Circle
D. Hexagon
Answer: B
The shape of the pantograph collector is a pentagon. It has a conducting strip that is pressed against contact wire with the help of springs.
17. There are typically three types of pantograph.
A. True
B. False
Answer: A
Open frame, faiveley, and crossed arm are typically three types of pantograph. The function of the pantograph is to maintain pressure and prevent vertical vibrations.
18. Full form of EMU is ____________
A. Electronics Multiple Unit
B. Electrical Multiple Unit
C. Electrical Multiple Usage
D. Electrical Multiple User
Answer: B
The full form of EMU is Electrical Multiple Unit. The trains having motor coaches and trailer coaches are known as EMU trains. They provide flexibility.
19. Who is known as the Father of Indian Railways?
A. Lord Dalhousie
B. Lord Ripon
C. Lord Boult
D. Lord Hero
Answer: A
Lord Dalhousie is known as the father of the Indian Railways. The first railway line connecting Bombay with Thane was laid in 1853.
20. Who built the first train?
A. Richardson
B. Rampa
C. Richard Trevithick
D. John Carry
Answer: C
Richard Trevithick built the first train in 1804. It was a steam locomotive train that used to carry 10 tonnes of iron from one place to another.
