Designing the voltmeter
Your table has been asked to design a circuit to determine the potential
difference across the light bulb in the circuit below.
Your boss has a few ideas but still has some questions. She's asked
each group at your table to look at part of the problem. Click below to
see your group's assignment:
Group 1:
One possible way to measure the potential difference across the
bulb is to hook up an voltmeter in parallel with the bulb (as shown
below):
The questions your boss has about this design are:
-
How does the potential difference across the meter compare to the potential
difference across the bulb?
-
Is this a good way to measure the potential difference across the light
bulb? Why or why not?
Once your group is satisfied with the answers to these questions, confer
with the other groups at your table to prepare the final
report to your boss.
Group 2:
One possible way to measure the potential difference across the
bulb is to hook up an voltmeter in series with the bulb (as shown
below):
The questions your boss has about this design are:
-
How does the potential difference across the meter compare to the potential
difference across the bulb?
-
Is this a good way to measure the potential difference across the light
bulb? Why or why not?
Once your group is satisfied with the answers to these questions, confer
with the other groups at your table to prepare the final
report to your boss.
Group 3:
One concern your boss has about adding a meter to the circuit might significantly
change the behavior of the circuit. Look at the two circuits below:
The questions your boss has are:
-
What effect does adding the meter to the circuit have?
-
How can the meter be designed so that this effect is minimized?
Once your group is satisfied with the answers to these questions, confer
with the other groups at your table to prepare the final
report to your boss.
The Final Report
Write a memo to your boss that explains how the voltmeter should used to
measure the potential difference across the bulb. Make sure that your memo
addresses all of the her questions.