Dell
- 555
- 0
given a long solenoid, with a radius of R (R<<L), a current of I flows through it. find the magnetic field at point A which is located at a distance of R from the solenoid on the solenoids line of symetry.
HOW DO I DO THIS??
the only thing i see that i think i need to do here is somehow use either biot savar or more likely ampere and solve it, but how?
the only problems i have had with solenoid were to find the field inside of it in which case i took a closed loop integral and used amperes law to get B=μNI/L=μnI
what i think i need to do(but have not managed) is use biot savar, and say that the total field can only be on the 'z' axis, along the centre of the the solenoid- since the rest cancel out due to symetry,
db=(μi/4pi)*dl/L^2
using pythagarus +++> L=sqrt(r^2+Z^2) while z is constant and r goes from 0 to R
z=R
after my integration i get (μi/sqrt(32)pi)*1/R^2
HOW DO I DO THIS??
the only thing i see that i think i need to do here is somehow use either biot savar or more likely ampere and solve it, but how?
the only problems i have had with solenoid were to find the field inside of it in which case i took a closed loop integral and used amperes law to get B=μNI/L=μnI
what i think i need to do(but have not managed) is use biot savar, and say that the total field can only be on the 'z' axis, along the centre of the the solenoid- since the rest cancel out due to symetry,
db=(μi/4pi)*dl/L^2
using pythagarus +++> L=sqrt(r^2+Z^2) while z is constant and r goes from 0 to R
z=R
after my integration i get (μi/sqrt(32)pi)*1/R^2