A long straight wire carries a current 20 A. A rectangular loop with two sides p
ID: 1696705 • Letter: A
Question
A long straight wire carries a current 20 A. A rectangular loop with two sides parallel to the straight wire has sides 2.5 cm and 10 cm, with its near side a distance 1 cm from the straight wire. Find the magnetic flux through the rectangular loop. The permeability of free space is 4 p × 10^-7 T · m/A.Answer in units of Wb.
The answer I got wrong on the problem was from the following work:
B=(4*pi*10^-7)*20/(2*pi*1) and then Flux_m=B(3.5*Area-1*area)[meters] I got 1.98*10^-7, what's wrong, and what's the right answer?
Explanation / Answer
The magnetic field in the long straight conductor is B = uoI/(2pr) =( 4p x 10^-7 H/m)(20 A)/(2p (0.01 m)) =0.0004 T. The magnetic flux is f = BA cos0 = (0.0004 T)(0.025 m)(0.10 m) = 1.0 x10^-6 T.m2