Lab #7: RL circuits
Theory:
1. What is and RL circuit?
2. Explain charging RL circuit.
3. Explain discharging RL circuit.
4. What is time constant τ?
Experiment:
• Measure L using the LCR meter. Measure R and RL using the DMM meter.
• Wire the RL circuit using the power amplifier and the RLC circuit board.
a) Charging the RL circuit: measure the voltage across resistor
•
•
Record Vmax using “smart tool”.
Fit data using exp fit ( y = Ae − Cx + B ). Fit will not work first time.
o Enter A=-Vmax and B=Vmax.
o Now we are fitting y = Vmax (1 − e − Cx )
o C=R/L, therefore τc=1/C
b) Discharging the RL circuit
• Fit data as before. It should work this time.
• τ d = 1/ C
Data analysis:
o Calculate τ±δτ using τ=L/R
o Calculate τc±δτc
o Calculate τd±δτd
o Compare τc and τd with τ.