Question

If a magnetic flux passes through a circular coil when its diameter D, what should be its diameter (in terms of D) so that only half as much flux passes through it in the same field? Assume that the magnetic field is uniform over the area in both cases.


I am totally lost! I Don't know where to start!

Answer 1

the area should be half the original

Area = pi r^2 = pi D^2/4
new area = pi D^2/8 = pi Dnew^2/4
Dnew ^2 = (1/2) D^2
Dnew = .707 D

Answer 2

ok I am confused, because I have the answer in the back of my book it says it is D/square root of 2