LR Circuit

This demonstration shows that in an LR circuit, the current lags the voltage by 90 degrees. The pico scope shows a plot of the voltage across the resistor and the entire circuit. The voltage across the resistor is proportional to the current in the circuit. Therefore, it can be seen that the current lags the voltage.

Setup:

Set the whiteboard on the lab table. Connect the webcam to the projector and set it up to view the whiteboard from above.

Using circuit scribe build the circuit shown above. Connect the function generator to the circuit. Connect channel A of the pico scope across the resistor and channel B of the pico scope across the whole circuit.

Set the function generator to the 1k sine wave range between 3 and 4 on the dial.

Open the pico scope software and turn on channel B. Set both channels to Auto and AC. Choose 50 micro s per division and 100 kS. At the bottom of the screen, Trigger should be set to Auto.

Turn on the function generator and observe the graph.

Notes:

Be sure that all the grounds for the pico scope are connected at the same point as the ground for the function generator!

Courses Used In:

• PHY 10320

• PHY 20435

• PHY 30220

Discussion and Polling Questions:

Coming Soon

Equipment Needed:

• Circuit Scribe Kit

• Whiteboard

• Two BNC to Banana Cables

• Pico Scope

• BK Precision 3010 Function Generator

• 2.7 k ohm Resistor

• 25 mH Inductor

• Demo Computer

• Webcam

• Ring Stand