Magnetic field on rotating electron.

[erhyde]

Homework Statement

an electron is rotating around a proton with a velocity of 2*10^6 m/s on circular path of diameter 5*10^-11 m. what is the magnetic field (B) ?
the centripetal force on the electron and the magnetic force should be equal and mv^2/r = Bqv or
B= mv/qr.

Homework Equations

centripetal force F=mv^2/r
magnetic force = Bqv.

 

[wzy7178]

B=4.55*10^5 t

 

[erhyde]

B=4.55*10^5 t

[STRIKE]can you explain a bit more?[/STRIKE]

nvm found the answer.

 

[erhyde]

new problem

a straight current carrying wire form a loop along its way. what is the magnetic field at the loops centre?
if the loop is rotated 90° about AB axis what will be the new magnetic field?
(sorry for the clumsy pic arrow shows direction of current. )
http://i1367.photobucket.com/albums/r785/erhyde/Untitled_zps91353383.jpg.