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Physics 145 Introduction to Experimental Physics I Instructor: Karine Chesnel Office: N319 ESC Tel: 801- 422-5687 [email protected] Office hours: on appointment Class website: http://www.physics.byu.edu/faculty/chesnel/physics145.aspx Your lab assignments 1. Prepare by reading the introduction material 2. Answer quiz questions (within the first half hour) and submit the sheet to your TA 3. Proceed to the experiments 4. Write a report of your findings for each experiment, in your lab notebook (individual reports) Lab 7-9 LRC circuits Impedances (see Lab 6) Resistor Capacitor Inductor I I I VC VL VR VL L V R RI In AC mode: I I 0 e VR RI 0e i t dI VC dt Q C 1 C Idt i t V R iL I 0 e i t VR I0e i t i C AC Impedances • Circuit in series: add impedances Z Z R Z L ZC Z R iL Z 1 i C Z e 1 R L C 2 1 tan L /R C 2 i “Gain” = output / input AC Gain • RLC circuit G V out V in Vin R Z R 1 R L C 2 2 Vout • RC circuit • RL circuit Vin Vout G V out V in Vin Vout R 1 R C 2 2 G V out V in R R L 2 2 Low-pass and high-pass filters • RC circuit • RL circuit Vin Vout G Vout V in Vout Vin R 1 2 R C G 2 V out V in Frequency response R R L 2 2 Frequency response High-pass Cutoff frequency f0 Low-pass 1 2 R C Cutoff frequency f0 R 2 L Time responses • RL circuit • RC circuit Vin When When Vout Vin V 0 V0 R I L dI V in 0 0 RI L dI Response time RL L R When dt dt Vout Vin When Vin V 0 V0 R I V in 0 0 RI Response time 1 C 1 C RC RC Idt Idt Resonator • RLC circuit G V out V in Vin R Z R 1 R L C 2 Resonance frequency Vout f0 Behavior of phase 90 width f 90 R 2 L Resonance Band-pass filter 1 2 LC 2 AC Impedances • Circuit in parallel: add inverses of impedances Z Z R 1 / Z L i C Notch filter 1 1 Z e i i L 1 R 1 / C L tan Frequency (Hz) ZC 1 Z R Z 1 2 1 1 R C L 2 Lab 7: AC impedance & high-pass filter A. Theory and calculation for RC filter • L7.1: Compute impedance Z, phase and gain G • L7.2: Check analytical results (Mathematica) • L7.3: Design RC filter with f0 ~ 1 - 5kHz B. Measurements • L7. 4, 5: set up the RC circuit • L7.6: measure gain G versus frequency f • L7.7: Plot G(f) and fit • L7.8: Behavior of phase Lab 8: Low-pass & high-pass filters A. Frequency response for RL filter • L8.1: Design a RL filter • L8.2: Set up the RL circuit • L8.3: Measure gain G versus frequency f, plot and fit • L8.4: compare experiment to theory B. Time response for RL filter • L8.5: response on a square-wave, measure tRL B. Time response for RC filter • L8.6: response on a square-wave, measure tRC, compare Lab 9: RLC resonator A. Measure & analyze RLC resonator • L9. 1: Design RLC series circuit for various f0 ~ 100Hz • L9.2: Set up the RLC circuit • L9.3: Measure gain G versus frequency f, plot and fit • L9.4: Compare experiment to theory • L9.5: Behavior of phase • L9.6: Behavior of Z, current I and gain value at resonance B. Parallel RLC circuit – notch filter • L9.7: Measure gain G versus frequency f, hole width C. Rms quantities and power dissipation • L9.8: measure Vrms, Irms and P, feel heating through resistor