Instructions. For these questions you will need to run a copy of the UBC-GIF magnetics dipole applet.
To start the applet in a new window click here.

NOTES:

• When drawing lines in the applet to obtain profiles, note that the A-B end points are always labeled from left-to-right, regardless of how you draw the line. Therefore, when looking at line profile graphs, you have to be careful about which way you are looking.
• Remember to click the "reset colours" button every time a change is made.

1. Make sure you know how to set up the applet by running the orientations quiz.




2. Starting configuration
   inclination=	0
   declination=	0
   length=	100
   data spacing=	1
   magnetic moment=	30
   depth=	10
   data type=	Bt

   Use the settings in the adjacent table for the following
   1. Generate a west-east line profile that crosses directly over the dipole (the little central dot). What are the minimum and maximum anomaly values?
   2. Generate a south-north line profile that crosses directly over the dipole. What are the minimum and maximum anomaly values?
   3. Carefully point to the line profile graph's vertical scale at halfway between the min and max values. What is the width of the anomaly at half its peak-to-peak amplitude?
   4. Change the depth to 5, click the "Reset colours" button. Now what is the anomaly's half-width? Does it look like there is a simple relation between depth and anomaly half-width?

3. Change back to a depth of 10 and make sure you are observing a S-N profile.
   1. Adjust the inclination to determine at what magnetic latitude the line profile appears anti-symmetric (equal positive and negative halves).
   2. When the S-N profile appears anti-symmetric, observe the surface plots of the negative and positive portions of the anomaly. What are the shapes of these portions of the anomaly? Do they have the same shape?

4. Reset everything to the "starting configuration." Adjust the inclination and declination to that of Vancouver, British Columbia (latitude and longitude of approximately 49N, 123W, for 2004). Now what are the max & min values of the anomaly ?

5. Reset again and adjust for Rio de Janeiro, Brazil (21S, 35W) and determine max & min values of the anomaly .

6. We want to determine if magnetic flux density values generated by the applet are consistent with theory:
   1. Use the dipole applet to confirm parameters in the magnetic units discussion referenced on the applet page (or here). Using parameters specified in that outline, you should get a maximum of 0.125 nT at a sensor that is 20 m above a dipole of strength 10 Am².
   2. Then estimate the expected maximum flux density that will be measured above a dipole of strength 30 Am², buried at 4 m depth (5 m from the sensor). What is your estimate, and what does the dipole applet give you? To what is this small discrepancy attributed?
7. (THIS NEEDS WORKING OUT) Consider the magnetic moment. If we are using a magnetic moment of 30, the object is a buried dipole of unit volume at depth 10 m (11 m from the sensor), and we are at Vancouver BC where the magnetic field strength is approximately 55,000 nT, what is the susceptibility of the dipolar object?

8. Consider vector components?

9. Consider gradient Bg, and resolution compared to total field.

10. Consider playing with depth?

11. Question to emphasize the B in air is plotted, not H.