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#### Lab Activities

The students look at the response of a series LRC circuit to a square wave driving voltage and to a sine wave driving voltage.

Specifically, for the square wave driving voltage, they are asked to:

1. sketch the current vs time displays for a circuit which is underdamped, critically damped and overdamped and compare them to the theoretically predicted curves;

2. sketch the current vs time displays for the circuit with the resistance in and out of the circuit and explain why the two displays have the shapes they do; and

3. experimentally determine the damping constant for the underdamped case and compare it to the theoretically predicted value.

For the sine wave driving voltage, they are asked to:

1. experimentally measure the natural oscillating frequency of the circuit and compare it to the theoretically predicted value;

2. take voltage vs driving frequency measurements for three different circuits and plot the resonance curves for those circuits and compare them to the expected shapes; and

3. take measurements of the phase difference between the current in the circuit and the driving voltage for the same three circuits used in the previous part and plot the phase differences vs driving frequency and compare them to the expected shapes.

For all of the plots dimensionless graphs are used.

Experimental results tend to be within 5-10% of the theoretically predicted values.

#### Equipment

 Number of set-ups available: 1 Per lab station: 1 oscilloscope 1 function generator 1 frequency counter/BNC cable 1 multimeter 1 resistance substitution box 1 capacitance substitution box 1 inductor 1 BNC to banana adaptor 8 banana leads

#### Notes

 Last Update: Site contact: largent@Dartmouth.EDU