PHY222, Elements of Physics II
Ampere's Law, 29 February 2008

Theory Requirements:

1. Demonstrate Ampere's law one more time for long, straight wires. Describe the relationship between our experimental parameters and the "mu zero" constant we measure.
2. State the value for "mu zero" we expect to find.

Comments on the Procedure:
As usual, summarize the major steps in the procedure - make an effort to avoid tangents. Do not blindly refer to a figure in the lab manual - where appropriate, give a brief description (such as wire placement, whatever will help you).

Pay special attention to "whose current" and "whose voltage" we are measuring. The current we will measure may be read straight from the power supply, like we did last week. The voltage we are interested in, however, is read from the multimeter attached to the magnetic sensor machinery.
Before you even begin making measurements:

1. Make sure the "unit number" written on your Ampere law experiment set and its power supply/amplifier are the SAME - if they aren't, weird things happen.
2. The switch to turn on the magnet sensor's power supply/amplifier is on its backside. Forgetting to turn this on causes weird things to happen.

Comments on Data:
DESCRIBE THE DATA TABLES and/or GRAPHS YOU PRESENT. This requires barely a sentence to state what the reader gets to find in each table or graph. Consider it some small evidence that you have some idea of what you were measuring and recording.
(Many of you are doing very well with this; others are neglecting it, and the grades reflect it.)

Results Checklist:

• Report your value for the graph's slope and its uncertainty.
• Report your value for "mu zero", and its uncertainty (both obtained from the slope and its uncertainty by multiplying by 2*pi).
• Report the percent difference, in comparing your "mu zero" value with the theoretical value. As a style tip - do not just blankly say, "The percent difference was_____." That can mean anything. The percent difference has to be in your measurement. It is better to say, "The percent difference in e/m was _________."
• Give a sample calculation for "mu zero" and its UNCERTAINTY.

Back