answer in T k vectorSolutionForces on a moving charge Electr

answer in T k vector

Solution

Forces on a moving charge

Electric = q*E
Magnetic = q*v*B

To get the value of B the two will be equal
qE=qvB
B=qE/qv = E/v = E/sqrt(2KE/m) = 8000/sqrt[(2 *3 * 1.6 * 10^-16)/9.1 * 10^-31] = 0.2463 mT

for direction
E is directed in -ve y therefore the force on a -ve electron will be in the +ve y direction

we want the direction of B to be in the -ve y direction to counteract the electric field
The magnetic force is perpendicular to the plane of v and B so
we want B directed in the -ve z direction (into the page)