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Welcome to blog help for PHY 122! Here's how it works. For each homework question and lab report we will make a post, this will probably contain a few tips on what the problems are about and how to solve them. If you are stuck on something then instead of emailing us directly you should post a comment in reply to the relevant post. We will try to guide you through tough points and help you understand the problems and the concepts behind them.
4 comments:
Question #4
magnitude of the average induced emf in the coil during that time.
Ok..I used the following equation:
NBAcos(62) all divided by the change in time.
I double checked my conversions from cm^2 to m^2 and uT to T.
The only problem I can think of is that the "change in area" isn't an appropriate to use for the Area.
Comments? Suggestions?
SKOR220,
The numbers in my WA problem are N=170, earth field B=50.0 uT, area change 45.0 cm^2, angle between earth field and plane of coil 25.0 degrees, and Delta t = 1.70 s. For the flux you want the angle between the normal vector (perpendicular to the coil area) and the B field. The given angle is that between the B field and the plane of the coil so you have to take 90 degrees minus this angle. I assume that's your 62 degrees. When I plug in my numbers, I get the correct answer for my WA problem. What you wrote seems correct. This is an "area changing" flux-change-induces-EMF problem so the change in area is what you need. I hope this helps. Did you try it for the values given in the textbook problem? Snce this is an odd number problem, you can find the answer at the back of the book for "its" numbers.
Okay, well my values are as follows:
N = 205
A = .0045m^2
B = 50E-6T
THETA = 62
dTime = 1.7
I plug the values into the following formula:
[NBA(cos 62)]/ dtime
then i divided by 1E-6 to covert to uV
I get 18.27(383404)
Webassign isn't accepting this value.
Omgoodness....I had forgetten to put my calculator back into degrees mode. How very silly...and how very frustrating.
Just now I decided to try using my computers calculator instead of my handheld. I noticed that my trig values were different and that's when it dawned on me.
Luckily you extended the assignment :) Thanks again for your help.
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