21. Insufficient rating of the machine can damage the windings.
A. True
B. False
Answer: A
The inadequate rating of the equipment can damage the winding and halt the machine’s operation. The windings can burn out and lead to the breakdown of the machine.
22. A circuit consists of two 7 F capacitors connected in series and a 12 H inductor. Determine the order of the circuit.
A. 1
B. 2
C. 0
D. 3
Answer: B
The order of the circuit is the number of memory/storing elements that are non-separable present in the circuit. In mathematics, the order is defined as the highest order derivate in the differential equation. The order of the circuit is 2 because two 7 F capacitors combine to form a single capacitor.
23. Calculate the steady-state temperature value for T(t)=1.5(1-e-17t).
A. 1.5
B. 4.8
C. 3.9
D. 2.4
Answer: A
The steady-state temperature value is obtained at t=∞.
The value of T(t) at
t=∞ is 1.5(1-e-∞)
=1.5(1-0)=1.5.
The term e-17t is an exponentially decaying function.
24. Calculate the quality factor for the R-C circuit connected to the cooling system if R=1 Ω and C=10 F.
A. 0.1
B. 0.2
C. 0.3
D. 0.4
Answer: A
The quality factor is defined as the ratio of the reactive power to the active power consumed. The resistor always absorbs active power and the capacitor absorbs the reactive power.
Quality factor=1÷RC
=1÷10=.1.
25. Calculate the heat absorbed by a 3 Ω resistor when 6 V is applied across it.
A. 12 W
B. 10 W
C. 8 W
D. 11 W
Answer: A
The resistor always absorbs active power and dissipates it in the form of heat.
Power absorbed by a 3 Ω resistor is 6×6÷3=12 W.
26. What is the unit of power?
A. Joule/sec
B. Joule/sec2
C. Joule/sec3
D. Joule/sec4
Answer: A
Power is defined as the rate at which work is done. The ratio of energy and time is power. It is expressed in Watt or Joule/sec.
27. Convert 20 ℃ into Fahrenheit.
A. 68 ℉
B. 58 ℉
C. 78 ℉
D. 48 ℉
Answer: A
Temperature can be expressed in Celsius and Fahrenheit. The Standard unit of the temperature is the Kelvin(K).
(20℃ × 9/5) + 32 = 68℉.
28. Convert 50℉ into Celsius.
A. 20 ℃
B. 10 ℃
C. 30 ℃
D. 40 ℃
Answer: A
Temperature can be expressed in Celsius and Fahrenheit. The basic unit of temperature in SI is the Kelvin. The formula used is
