# Flux through loop around solenoid

## Homework Statement

A simple loop of 5 cm radius encompasses the middle turns of a long coil. The coil has 2500-turns,
is of length 1 m and radius 1 cm, and carries a current of 10 Amps. What is the magnetic flux through the single loop?

## Homework Equations

B=μIN/L with L=1: B=μIN
flux=∫B.dA

## The Attempt at a Solution

flux= μIN*A(loop)= 4π*10^-7*10*π*(5*10^-2)^2
This is not right apparently

the actual answer uses the area of the solenoid. Why is that? FLux is the B field dotted with perpendicular area, so why is it the solenoid area? That means that flux is independent of the loop's size!

Related Introductory Physics Homework Help News on Phys.org
That is correct.
Flux DENSITY = B = Webers/m^2
Flux is in Webers = B x A.
The solenoid is what is producing the flux and it is constant = B x Area of solenoid

But I'm looking for the flux through the loop!

tiny-tim
truesearch is right …
there's no magnetic field (and no flux) outside the solenoid 