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18th October 2011

 

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Module 9.4

LCR Series Quiz

What you should know.

  • After studying Module 9, you should:
  • • Be able to recognise LCR Series circuits and describe their action using phasor diagrams and appropriate equations.
  • • Be able to describe LCR Series Circuits at resonance and the conditions for series resonance.
  • • Be able to carry out calculations on LCR series circuits, involving reactance, impedance, component and circuit voltages and current.
  • • Be able to Describe voltage magnification and calculate Q factor in LCR Series Circuits

 

Try our quiz, based on the information you can find in Module 9. Submit your answers and see how many you get right. If you get answers wrong, just follow the hints on the answers page to find the right answer and learn about Series LCR circuits as you go.

1.

Fig 9.4.1With reference to Fig 9.4.1 the resonant frequency of the circuit will be approximately:
  • a) 71.2kHz
  • b) 444.3MHz
  • c) 2.251 kHz
  • d) 7.12MHz

2.

With reference to Fig 9.4.1, what will be the maximum supply current?
  • a) 70mA
  • b) 250mA
  • c) 500mA
  • d) 14.14mA

3.

With reference to Fig 9.4.1, what will be the approximate voltage across C at resonance?
  • a) 177V
  • b) 70V
  • c) 1.7kV
  • d) 353V

4.

With reference to Fig 9.4.1, what is the Q factor of the circuit?
  • a) 3.535V
  • b) 1.4
  • c) 0.707
  • d) 3.5

5.

Which of the following statements about a series LCR circuit is true?
  • a) At resonance, the total reactance and total resistance are equal.
  • b) The impedance at resonance is purely inductive.
  • c) The current flowing in the circuit at resonance is at maximum.
  • d) The impedance at resonance is at maximum.

6.

If the values of L and C in a series LCR circuit are doubled, what will be the effect on the resonant frequency?
  • a) It will be halved.
  • b) It will not be changed.
  • c) It will double.
  • d) It will increase by four times.

7.

With reference to Fig 9.4.2, which diagram shows a series LCR circuit at resonance?Fig 9.4.2
  • a) Diagram a
  • b) Diagram b
  • c) Diagram c
  • d) Diagram d

8.

What words are missing from the following statement? The impedance of series LCR circuit at resonance will be _______ and equal to the circuit _______ .
  • a) Minimum and resistance.
  • b) Maximum and resistance.
  • c) Minimum and reactance.
  • d) Maximum and reactance.

9.

Fig 9.4.3aWith reference to the graph of voltages and current in a series resonant circuit shown in Fig 9.4.3a, What quantity is represented by line A?
  • a) Circuit impedance.
  • b) Voltage across the capacitor.
  • c) Supply voltage.
  • d) Circuit current.

10.

Fig 9.4.3bWith reference to the graph of voltages and current in a series resonant circuit shown in Fig 9.4.3b, What quantity is represented by line B?
  • a) Circuit impedance.
  • b) Voltage across the capacitor.
  • c) Supply voltage.
  • d) Circuit current.