A particle of mass and charge moves with a constant velocity along the positive -direction

PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

A particle of mass

m

and charge

q

moves with a constant velocity

v

along the positive

x

-direction. It enters a region containing a uniform magnetic field

B

directed along the negative

z

-direction, extending from

x = a

x = b

. The minimum value of

v

required so that the particle can just enter the region

x > b

is [2002S] (1)

\frac{qbB}{m}

(2)

\frac{q(b-a)B}{m}

(3)

\frac{qaB}{m}

(4)

\frac{q(b+a)B}{2m}