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## 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!