rc, lr, and lc circuit labs peggy bertrand oak ridge high school oak ridge, tn [email protected]
TRANSCRIPT
College Board ObjectivesB C
RC CIRCUITS
RC Circuit Lab Equipment
Low tech
• Capacitors• 100mF to 300 mF
• Resistors• 15,000 W or higher
• D-Cells• Knife switch (spdt)• Connecting wires• Voltmeter• Kid with a pencil
High tech
• Add a Pasco or Vernier system with a voltage probe
RC Circuit – low tech
$1.00
$2.00
$3.00 $5.00
<$1.00$15.00
RC Circuit – high tech
$1.00
$2.00
$3.00$5.00
<$1.00$350 - $425
RC Circuit Lab – student instructions
Build an RC circuit that can undergo charge and discharge cycles with a flip of the switch.
Use capacitors of between 100 mF and 300 mF, and resistors of between 10,000 W
and 100,000 W.
Collect voltage data over the resistor and over the capacitor for the charge and the
discharge cycles and produce graphs of these data.
Compare the predicted and graphically determined time constants for your circuit .
Repeat for a second circuit with a different capacitive time constant.
Your report must include:
• Your graphs.
• Circuit diagram
• Graphically-determined capacitive time constants.
• Predicted capacitive time constants.
• Comparison of time constant values.
Circuit setup
A
B
V
V
RC Circuit Charge and Discharge Data
This circuit was built with a 15000 W resistor and a 1000 mF capacitor.Calculated time constant: 15 s. Graphical time constant: 14 s.
RC
Circuit Q
uestion
LR CIRCUITS
LR Circuit Lab
OR
LR Circuit Setup
V
A
LR Circuit Results
LR Circuit Results
Alternative Student-Built Circuit
V
V
RC
and LR C
ircuit Question
LC CIRCUITS
LC Circuit Lab Equipment
OR
AND
LC Circuit – Instructions to Students• Build an LC circuit with an inductor, capacitor, DC power
supply, and a single-pull double-throw switch. • The switch should be used to charge the capacitor using
the DC voltage source when it is in one position, and to discharge the capacitor through the inductor when it is in the other position.
• There is resistance in your inductor that will damp the oscillations, so don’t add any additional resistance! (You are really building an LRC Circuit)
• Rapidly sample the voltage across the capacitor to obtain a damped oscillator curve.
• Compare the period you obtain to the predicted period.
Circuit Setup• Capacitor charges when
switch is in position A.• When moved to position B,
an LRC circuit undergoes damped oscillation with a period predicted by:
B
A
V
LCT 2
C
e
LC (well, really LRC) Circuit Results
Data taken with Pasco Science Workshop 750, sampled at 5000 Hz
LC Circuit Question
Thank you for your attention…