Cracking the SAT Physics Subject Test

(Marvins-Underground-K-12) #1

Since FB is always perpendicular to v, the particle will undergo uniform circular


motion; FB will provide the centripetal force. Notice that, because FB is always


perpendicular to v, the magnitude of v will not change, just its direction.


The Skinny on Magnetic Fields
FB is always perpendicular to both v and B.

Magnetic forces cannot change the speed of an object, only its direction.

The magnetic field does no work on any charge.

The radius of the particle’s circular path is found from the equation FB = FC.



  1. A particle of charge −q is shot into a region that contains an

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