Peoples Physics Book Version-2

15.3. Effects of Magnetic Fields http://www.ck12.org

15.3 Effects of Magnetic Fields

Force on a Charged Particle

As moving charges create magnetic fields, so they experience forces from magnetic fields generated by other
materials. The magnitude of the force experienced by a particle traveling in a magnetic field depends on the charge
of the particle(q), the velocity of the particle(v), the strength of the field(B), and, importantly, the angle between
their relative directions(θ):

FB=qvBsinθ [3] Force on a Charged Particle

There is asecond right hand rulethat will show the direction of the force on a positive charge in a magnetic field:
point your index finger along the direction of the particle’s velocity. If your middle finger points along the magnetic
field, your thumb will point in the direction of the force. NOTE: For negative charge reverse the direction of the
force (or use your left hand)

For instance, if a positively charged particle is moving to the right, and it enters a magnetic field pointing towards
the top of your page, it feels a force going out of the page, while if a positively charged particle is moving to the left,
and it enters a magnetic field pointing towards the top of your page, it feels a force going into the page: