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18th October 2011

 

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Module 5.5

Module 5 Quiz

What you´ll learn.

  • After studying this section, you should be able to:
  • • Describe phase relationships in sine waves applied to capacitive, inductive and resistive circuits.
  • • Describe the representation of sine waves using phasors.
  • • Interpret phasor diagrams relating to voltage current and phase relationships in ac circuits.
  • • Calculate values in ac circuits using phasor diagrams.

 

Try our quiz, based on the information you can find in Module 5. Hopefully it won't be too difficult. Submit your answers to see how well you did. If you got any answers wrong, you´ll be told where to find the right answer, so you can learn more about AC circuits and Phasors before you have another try.

1.

In an inductor, an increase in the value of the internal resistance has the effect of:
  • a) Increasing the inductance.
  • b) Decreasing the phase difference between the inductor voltage (VL and current (IL).
  • c) Decreasing the inductance.
  • d) Increasing the phase difference between the inductor voltage (VL and current (IL).

2.

In a capacitor
  • a) Current leads voltage by 90°.
  • b) Voltage leads current by 90°.
  • c) Current Lags Voltage by between 0° and 90°.
  • d) Voltage leads current by between 0° and 90°.

3.

Which property of a sine wave does the length of a phasor represent?
  • a) Frequency.
  • b) Phase.
  • c) Amplitude.
  • d) Instantaneous value.

4.

Phasors Refer to Fig. 5.5.1: Which of the following statements about Fig 5.5.1 is true?
  • a) All the waves depicted have the same frequency and same amplitude.
  • b) All the waves depicted have the same phase and same frequency.
  • c) All the waves depicted have the same shape and same frequency.
  • d) All the waves depicted have the same phase and same shape.

5.

PhasorsRefer to Fig 5.5.2: What is the phase difference θ between the supply voltage and the supply current?
  • a) 53°
  • b) 37°
  • c) 30°
  • d) 59°

6.

PhasorsRefer to Fig 5.5.3: Which of the phasor diagrams describes a CR series Circuit?
  • a) Diagram a.
  • b) Diagram b.
  • c) Diagram c.
  • d) Diagram d.

7.

Refer to Fig 5.5.1: If phasor P2 represents 5V and phasor P3 represents 11V, what is the approximate angle between P2 and P3?
  • a) 27°
  • b) 67°
  • c) 71°
  • d) 63°

8.

In a parallel LCR circuit, which of the following properties is used as the reference phasor?
  • a) Supply current (IS ).
  • b) Reactive voltage (VC − VL) .
  • c) Supply voltage (VS) .
  • d) Reactive voltage (VL − VC) .

9.

A phasor representing a 1kHz sine wave will rotate through how many complete radians in one second?
  • a) 360,000
  • b) 6283
  • c) 1000
  • d) 3142

10.

In a phasor diagram, the frequency of each of the waves shown by the phasors is:
  • a) The same for all waves, and shown by the point of origin of the phasors.
  • b) Different for each wave ,and proportional to the different lengths of the phasors.
  • c) Different for each wave, and shown by the change in angle of the phasors.
  • d) Not shown.