309A Circuit Theory and Calculations 2

Question 1

What is the resonant frequency of a series RLC circuit with L = 10 mH and C = 100 µF?

Accepted Answer

159.2 Hz

Answer

79.6 Hz

Answer

318.3 Hz

Answer

500 Hz

Question 2

A three-phase balanced load draws 30 A per phase at 600 V line-to-line. What is the total apparent power?

Accepted Answer

31.18 kVA

Answer

18 kVA

Answer

36 kVA

Answer

54 kVA

Question 3

What happens to the total capacitance when capacitors are connected in parallel?

Accepted Answer

It increases (values add)

Answer

It decreases

Answer

It stays the same

Answer

It becomes the reciprocal sum

Question 4

A motor draws 25 A at 480 V three-phase with a power factor of 0.85. What is the real power consumed?

Accepted Answer

17.66 kW

Answer

10.2 kW

Answer

20.78 kW

Answer

24.48 kW

Question 5

What is the time constant of a circuit with a 500 µF capacitor and a 2 kΩ resistor?

Accepted Answer

1.0 s

Answer

0.1 s

Answer

0.5 s

Answer

2.5 s

Question 6

In a delta-connected three-phase system, what is the relationship between line current and phase current?

Accepted Answer

IL = IP × √3

Answer

IL = IP

Answer

IL = IP / √3

Answer

IL = IP × 3