51. During short circuit condition, the voltage is equal to ________
A. 2 V
B. 0 V
C. 1 V
D. 3 V
Answer: B
During the short circuit condition, the voltage is equal to zero volts. According to Ohm’s law, V=IR=0 V. The value of the current can be positive, negative, or zero.
52. When 5 A current flows into the positive terminal of voltage source 6 V. Calculate the power delivered by the source.
A. -30 W
B. 36 W
C. -43 W
D. 50 W
Answer: A
When the current enters the positive terminal of an element it will always absorb the power and when the current leaves the positive terminal it will deliver the power. Power delivered is
-5×6=-30 W.
53. When 10 A current leaves the positive terminal of resistance 5Ω. Calculate the power absorbed by the resistance.
A. -308 W
B. 500 W
C. -63 W
D. 60 W
Answer: B
When the current enters the positive terminal of an element it will always absorb the power and when the current leaves the positive terminal it will deliver the power. The power delivered is
100×5=500 W.
54. Calculate the equivalent inductance when two inductors are connected in a series of values 4 H and 9 H.
A. 13 H
B. 10 H
C. 11 H
D. 12 H
Answer: A
When two inductors are connected in series their equivalent inductance is equal to the sum of the individual inductances.
Leq=L1+L2=4+9=13 H.
55. Calculate the equivalent resistance when three resistances are connected in a series of values 8 Ω, 3 Ω, and 1 Ω.
A. 12 Ω
B. 18 Ω
C. 15 Ω
D. 16 Ω
Answer: A
When three resistances are connected in series their equivalent resistance is equal to the sum of the individual resistances.
Req=R1+ R3+R2=12 Ω.
56. Calculate the active power in an inf Ω resistor with 0 current flowing through it.
A. inf MW
B. 4.44 MW
C. 12 MW
D. 6.18 MW
Answer: A
The resistor is a linear element. It only absorbs real power and dissipates it in the form of heat. The voltage and current are in the same phase in the case of the resistor so the angle between V & I is 0°.
P=I2R=0×0×inf=inf MW.
57. When 15 A current flows into the positive terminal of voltage source 60 V. Calculate the power delivered by the source.
A. -900 W
B. 936 W
C. -943 W
D. 950 W
Answer: A
When the current enters the positive terminal of an element it will always absorb the power and when the current leaves the positive terminal it will deliver the power.
Power delivered is -15×60=-900 W.
58. Source transformation is not valid for ___________
A. Ideal voltage source
B. Ideal current and voltage source
C. Practical voltage source
D. Practical current source
Answer: B
Source transformation is not valid for an ideal current and voltage source. The internal resistance for ideal voltage and current source is zero due to which source transformation is not valid.
