Maple TA Quiz 19.1

Did anyone get #3 and 4...i cannot seem to get the equation right...i looked at the lecture notes but its not clicking....pls help

1) cos0 *(magnetic field)*(pi*r^2) … answer is positive… convert the radius from centimeter to meters.
2) ((magnetic field)*(area))/2 … answer is negative
3) 1/given number … answer is negative
4) (L*v*magnetic field)/resistance … answer is negative… convert centimeter to meters

The #2 above is not correct, follow along with sheet 3:

magnetic flux = B*A
The induced emf is = - (magnetic flux/change in time)
so, basically instead of dividing by the 2 they said to divide by above, you divide by the number of seconds given in your question.

no matter how many times i've tried number 2 I can't get it rite! please help!! ><

A= 43.51cm^2 * 0.0001m= 0.04351m^2
B= 0.1425
deta t= 0.2014s
epsilon= (B*A)/delta t
answer -0.00308

thanks i got it! =)

For number 4 why do we divide by resistance? I got the answer from the equation, and I see the equation int he lecture notes,, but there's no resistance in it, so how did you figure that one out? Thanks.

problem 4 is not coming out right for me, I am going over the notes, but i keep getting it wrong