Hello everybody and thanks so much for your help,(adsbygoogle = window.adsbygoogle || []).push({});

(I know I have to improve my English)

here is my big problem concerning 3 formula's :

(It's just the beginning)

-first at all,we have a magnetic field B created by the circulation of a current I into a spire (with a spoke a) on a point at a distance b of the plane of the spire on his axis

-->B(b) = µo I a²/ 2(a²+b²)^3/2

-then,we have an other magnetic field with 2 identical coils separated with a distance 2b just to be in the same axis and to have the same current I circulating in the same direction.

-->B(x)=B1(x) + B2(x) = µo I a²/2 ((1/(a²+b+x)²)^3/2) + (1/(a²+(b-x)²)3^/2)).

-It's possible to give a Taylor's development of this expression,so we obtain the Helmholtz condition (I don't understand that very well) and the magnetic field is given by:BH=8µ0NI/5 (square root 5)a.

Now I have to find these 3 expressions:

aid of the Biot-Savart law,how could you obtain the expression of the magnetic field created by a current I circulating into a spire on a point of the normal axis in the plane of the spire and passing through his centre.

>>From this expression,how could you deduce the magnetic field on any point of this axis of an Helmholtz assembly.You have to give the taylor's development in the powers of x around the centre of the assembly and deduce the Helmholtz condition 2b=a which verifyes an homogeneous magnetic field in the assembly.Which is the value of the magnetic field?At which distance of the centre,on the axis of the assembly,is the field different of 1% from his value at the centre?

(*concerning the assembly,we use a Hall Effect probe too)

Please help me because I don't understand anything.I am desperate .What is the Helmholtz condition?Why is that so important?Could you please help me for the questions (principally from>>>)

Thank you very much!!!

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Magnetic induction

**Physics Forums | Science Articles, Homework Help, Discussion**