Physics 196, Week 6 Lab, Introduction to Circuits
1
I. Ranking Tasks: Before your group begins the lab, make some predictions based on what you or your
group understands of electricity at this point. Complete this section before you begin the lab. For each
figure below, assume the batteries are identical and all light bulbs are the same. After the switch is closed,
rank in order, from brightest to least, the brightness of the bulbs A to D. Explain your reasoning. Also
rank the voltage (potential difference) that you might measure across each light bulb A to D for the
following circuits. You will not be penalized if you get this section wrong; however, you will be
penalized if you don’t correct any faulty reasoning you may have about circuits. Do not get any
electrical components until this section is completed!
1.
Light bulb ranking:______________________
Potential difference ranking:________________
Reasoning:
3.
Light bulb ranking:______________________
Potential difference ranking:________________
Reasoning:
2.
Light bulb ranking:______________________
Potential difference ranking:________________
Reasoning:
4.
Light bulb ranking:_____________________
Potential difference ranking:________________
Reasoning:
Physics 196, Week 6 Lab, Introduction to Circuits
5.
Light bulb ranking:_____________________
Potential difference ranking:________________
Reasoning:
7.
Light bulb ranking:________________________
Potential difference ranking:________________
Reasoning:
9.
2
6.
Light bulb ranking:_____________________
Potential difference ranking:________________
Reasoning:
8.
Light bulb ranking:_______________________
Potential difference ranking:________________
Reasoning:
Physics 196, Week 6 Lab, Introduction to Circuits
3
Light bulb ranking:_________________________
Potential difference ranking:________________
Reasoning:
Explain which criteria was or were used to determine the ranking of the brightness of the bulb?
Explain which criteria was or were used to determine the ranking of the potential difference across each
light bulb?
II. Experimental: Build each circuit (1 to 9) and determine the actual ranking of the light bulb
brightness. Also use a digital multi-meter and measure the voltage across each light bulb (A to D).
Materials: 4 light bulbs, 8 alligator clip wires, 2 batteries, and 1 switch.
Table I: Experimental Light Bulb Data
Circuit Observed brightness
ranking
Voltage measured across the light bulb
A
B
C
Observed voltage
ranking
D
1
2
3
4
5
6
7
8
9
Compare your predicted ranking to the observed ranking. At this point, do you need to modify your
reasoning as to what factors determines the brightness of the bulbs? If so, write your modified reasoning.
Then use it to complete the scenario section.
Physics 196, Week 6 Lab, Introduction to Circuits
4
III. Scenario
Build and draw the following circuit.
1. A = B > C > D
2. A > B = C > D
3. Level III Optional to the only group that builds this circuit, or Level II Optional if more than one group
builds this, or no Level optional if every group builds this circuit: A > B > C > D