magnetic fields physics II?

A uniform magnetic field is directed towards the positive x-axis as shown in the figure. An alpha particle (Helium nucleus) enters the field traveling at 3 x 106 m/s in the negative y-direction.

i) Calculate the radius of the circular path executed by the alpha particle.

ii) as seen from the right (i.e. along x-axis towards the origin), will the circular path be clockwise or counterclockwise?

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&sou...

It's number one on exam III.

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  • 7 years ago
    Best Answer

    (i) the particle undergoes the electromagnetic force F = q v X B

    where (v is the velocity and B the field, all are vectors) and q= 2e

    F is orthogonal to v then the work of F is 0

    And If you neglect the weight of the particle, you can write (a is the acceleration):

    m a = q v X B =>value of a: a=q/m v B

    work of F is 0 => the magnitude of v is constant

    the motion is circular and uniform, the a= V^2 / R = q/m vB

    then R = mv/(qB) then use your values..

    (ii) the velocity is always orthogonal to B... and use the right hand rule to find the direction of the path : which is clockwise

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