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June StudentZone Quiz Solution

Discussion created by bsiegel Employee on May 23, 2018

Please find here the answers for the StudentZone article June 2018.

 

Question 1:

Using equations (5) and (6) determine the impedance (Zcircuit) and phase (θ) relationship of the current relative to the voltage for a RC circuit by replacing the A and B variables with proper values.

Answer 1:

We consider the following equations for RC circuit:

  • impedance:
  • phase relationship of the current relative to the voltage: 

The impedance of the capacitor is: 

The impedance of the resistor is: 

Therefore, we can compute the circuit impedance as follows:

                                                   

And phase:  

Where:  is known as the capacitive reactance of the capacitor.

Question 2:

For RC circuit in Figure 6, measure the time difference and calculate the phase θ offset at 1000 Hz frequency.

Answer 2:

Taking into consideration the setup made for the RC circuit measurements, additional steps must be followed:

  • Set AWG CHA to 1000 Hz and the time / div to 0.2 msec/div.
  • Put a first marker at the neg. to pos. zero crossing location for the CA-V ( VR1+ VC1) signal. Put a second marker at the nearest neg. to pos. zero crossing location for the Math ( VR1 ) signal. Record the time difference (∆t) and calculate the phase angle(θ). Note ∆t maybe a negative number. Does this mean the phase angle leads or lags?

To remove the markers for the next measurement click on the red Stop button.

  • Put a first marker at the neg. to pos. zero crossing location for the CA-V ( VR1+ VC1) signal. Put a second marker at the nearest neg. to pos. zero crossing location for the CB-V ( VC1 ) signal. Record the time difference (∆t) and calculate the phase angle (θ).
  • Put a first marker at the neg. to pos. zero crossing location for the Math ( VR1) signal. Put a second marker at the nearest neg. to pos. zero crossing location for the CB-V ( VC1 ) signal. Record the time difference and calculate the phase angle.

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