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Unformatted text preview: re finished using it. To d ischarge a capacitor, use an insulated w ire
t o briefly connect one of the term inals to the other.
M ake sure all of your capacitors are uncharged before starting the exploration. Exa m ine
each elem ent of the circuit b efore y ou build it. H ow d o you know if the battery and the
bulb are "good "? Connect Circuit I to use as a reference.
N ote: Make sure the + terminal of the battery is connected to the + terminal of the
capacitor! These capacitors are only d esigned to charge one w ay. If you connect the
capacitors up the w rong w ay, the capacitance w ill change in an unpred ictable m anner.
Close the circuit and observe how the brightness of the bu lb changes over tim e. H ow
long d oes it take for the bulb to turn off?
Connect Circuit II using the capacitor from Circuit I along w ith a capacitor w ith a
d ifferent capacitance. D o not close the circuit yet. D o you think the bulb w ill light w hen
the circuit is closed ? Record your reasoning in you r journal. N ow, close the circuit.
Record your observations and explain w hat you saw using conservation of charge and
the concept of potential d ifference. Does the ord er that you connect the tw o capacitors
and the bulb in the circuit m atter? Try follow ing one capacitor w ith the other capacitor
and then the bulb. Try sw itching the tw o cap acitors.
When the brightness of the bulb no longer changes, how are the the potential
d ifferences across the circuit elem ents related ? Check this u sing the DMM, set for
potential d ifference (Volts). Use the concept of energy conservation to explain w hat
Connect Circuit III using the tw o capacitors you used in Circuit II. D o not close the
circuit yet . Do you think the bulb w ill light w hen the circuit is closed ? Record your
reasoning in your journal. N ow, close the circuit. Record your observations and explain
w hat you saw using conservation of charge and the concept of potential d ifference. Use
the DMM to check the relationship betw een the potentia l d ifferences across the
elem ents of this circuit. Explain w hat you observe.
Develop a plan for m easuring the tim e that it takes for the bulbs in Circuits I, II, and III
to turn off, if they light at all. 73 CIRCUITS WITH TWO CAPACITORS – 1302Lab3Prob4 M EASUREMEN T
U se your m easurem ent plan to recor d how long it takes for the light bulb to go off for
each circuit. Use “0 second s” for any bulbs that d id not light. What are the
uncertainties in these m easurem ents? A N ALYSIS
Rank the actual tim e it took each bulb to turn off. Do all the bulbs init ially light? Do all
the bulbs eventually go off? CON CLUSION
H ow d id your initial ranking of the tim e it w ould take for the bulbs to go out com pare
w ith w hat actually occurred ? Use conservation of charge, conservation of energy, and
the concept of potential d ifference to explain your results.
Com pare the reasoning you used in the exploration section to predict w hether the bulbs
w ould light in each circuit to the und erstand ing you now have. If your reasoning has
changed , explain w hy it changed . 74 CHECK YOUR UN D ERSTAN D IN G LAB 3: ELECTRICAL EN ERGY AN D CAPACITORS
For each of the arrangements of identical capacitors shown below:
1) Rank them in terms of the amount of time they can light a light bulb. Assume that the leads shown have
been connected to a 6 Volt battery and then removed from the battery and connected to a light bulb.
2) Calculate the potential difference between the terminals of each capacitor. Assume that the leads shown
have been connected to a 6 Volt battery and that the capacitance of each capacitor is 10 C.
3) Calculate the amount of energy stored in each capacitor and the total energy stored in each arrangement of
capacitors. Assume that the leads shown have been connected to a 6 Volt battery and that the capacitance
of each capacitor is 10 C Arrangement 2 Arrangement 1 Arrangement 3 Arrangement 4 75 CHECK YOUR UN D ERSTAN D IN G LAB 3: ELECTRICAL EN ERGY AN D CAPACITORS 76 TA Name: PHYSICS 1302 LABORATORY REPORT
Name and ID#:
Date performed: Day/Time section meets: Lab Partners' Names: Problem # and Title:
Lab Instructor's Initials:
Grading Checklist Points LABORATORY JOURNAL:
(individual predictions and warm-up completed in journal before each lab session)
(measurement plan recorded in journal, tables and graphs made in journal as data is
collected, observations written in journal) PROBLEM REPORT:*
(clear and readable; logical progression from problem statement through conclusions;
pictures provided where necessary; correct grammar and spelling; section headings
provided; physics stated correctly)
DATA AND DATA TABLES
(clear and readable; units and assigned uncertainties clearly stated)
(results clearly indicated; correct, logical, and well-organized calculations with
uncertainties indicated; scales, labels and uncertainties on graphs; physics stated correctly)
(comparison to prediction & theory discussed with physics stated correctly ; possible
sources of uncertainties identified; attention called to experimental problems)
TOTAL(incorrect or missing statement of physics will result in a maximum of 60% of the
total points achieved; incorrect grammar or spelling will r...
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This document was uploaded on 02/23/2014 for the course MANAGMENT 2201 at University of Michigan.
- Spring '14