- Watch the videos
- Week 2 Video Lecture – Capacitive Reactance
- Consider the circuit below:
For each value of the frequency in the chart below, perform calculations for Ic, Vc and Xc.
Frequency Calculated I_{c} Calculated V_{c} Calculated X_{C} Measured I_{C} Measured V_{c} X_{C} (From Measured) 100 Hz 500 Hz 1000 Hz 1500 Hz 10000 Hz 20000 Hz
- Construct the circuit with MultiSIM using a 10% tolerance for the capacitor. Replace the AC source shown with the Agilent Function Generator.
- *Note: One way to set the tolerance on a component is to do the following:
- Double-click on the component and select the Value tab.
- Select or enter the desired value in the Tolerance field and click OK.
- Complete the chart by adjusting the values of frequency and measuring Ic and Vc using the Agilent Multi-meter and then from these values calculating the value of Xc in the last column.*Note: Current is measured in series with the capacitor and voltage is measured in parallel (across) the capacitor. Capture screenshots showing the measured values of Ic and Vc using the Agilent Multi-meter.
- Discuss the following:
- Describe the relationship between the frequency and the capacitive reactance.
- What effect does frequency have on Ic and Vc for a fixed value of capacitance in this circuit?
- For a frequency of 1000Hz, what would be the effect of increasing the value of the capacitor on the current Ic and the voltage Vc?
- Why is it necessary to measure current in series with a device and voltage across it?
- Why is it necessary to determine X_{c} from measured values of current and voltage as opposed to measuring it directly with a digital multi-meter? (It may be helpful to perform research on the internet to gain more insight into the topic of this question.)
Watch the videos
Week 2 Video Lecture – Capacitive Reactance
Consider the circuit below:
For each value of the frequency in the chart below, perform calculations for Ic, Vc and Xc.
Frequency |
Calculated Ic |
Calculated Vc |
Calculated XC |
Measured IC |
Measured Vc |
XC (From Measured) |
100 Hz |
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500 Hz |
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1000 Hz |
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1500 Hz |
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10000 Hz |
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20000 Hz |
Construct the circuit with MultiSIM using a 10% tolerance for the capacitor. Replace the AC source shown with the Agilent Function Generator.
*Note: One way to set the tolerance on a component is to do the following:
- Double-click on the component and select the Value tab.
- Select or enter the desired value in the Tolerance field and click OK.
Complete the chart by adjusting the values of frequency and measuring Ic and Vc using the Agilent Multi-meter and then from these values calculating the value of Xc in the last column.
*Note: Current is measured in series with the capacitor and voltage is measured in parallel (across) the capacitor. Capture screenshots showing the measured values of Ic and Vc using the Agilent Multi-meter.
Discuss the following:
- Describe the relationship between the frequency and the capacitive reactance.
- What effect does frequency have on Ic and Vc for a fixed value of capacitance in this circuit?
- For a frequency of 1000Hz, what would be the effect of increasing the value of the capacitor on the current Ic and the voltage Vc?
- Why is it necessary to measure current in series with a device and voltage across it?
- Why is it necessary to determine Xc from measured values of current and voltage as opposed to measuring it directly with a digital multi-meter? (It may be helpful to perform research on the internet to gain more insight into the topic of this question.)