# Magnetic field strength at point P around a solenoid

Tags:
1. Oct 12, 2015

### ealbers

I have a solenoid, Length L, number of turns N, ampers I Radius R

I have a Point P(x,y,z) anywhere around said solenoid.

How can I calculate the field strength at point P, note it is OUTSIDE the solenoid, and could be anywhere outside. Assume the origin is the center of the solenoid, lets assume the axis of the solenoid is along the X axis, -L/2 to +L/2

Thanks!
Eric

2. Oct 13, 2015

### Hesch

I assume that the solenoid has no (iron)core:
You must use a numeric/computer calculation, using Biot-Savart. This calculation should be exact, with a high precision data format.
You cannot use Amperes law, because here the mean strength along a circulation path is calculated.