T or F. A charged particle always move with a circular motion if its motion is initially perpendicular to a B-field.

Question

T or F. A charged particle always move with a circular motion if its motion is initially perpendicular to a B-field.

souvik · Answer

yes...the force on a moving charge $$F=qv \times B$$...
or $$F=qvBsin \theta $$
as the motion of the charge is initially perpendicular to B(magnetic field)...so $$\theta =90^{0}$$ ..
so force is also perpendicular to the initial velocity...
so it will move with a circular motion..

anonymous · Answer

but it said "is initially perpendicular"...  the word initially is weird

souvik · Answer

it means theta=90 degree

anonymous · Answer

i know that perpendicular is that... but initially?

anonymous · Answer

cuz the book said: is always perpendicular not always circular

anonymous · Answer

the words are like invert

souvik · Answer

the charge enters in magnetic field perpendicularly..

anonymous · Answer

i understand but why is initially?

souvik · Answer

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souvik · Answer

the charge is at point A..its velocity is indicated by the arrow due north,,B is directed into the page..so force is directed left which generates the centripetal force...

anonymous · Answer

ohhh! cool, thanks!

souvik · Answer

anytime...

souvik · Answer

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfor.html#c2 it may help u...

anonymous · Answer

pretty nice