Electrons taveling at a velocity of `2.4xx10^(6) ms^(-1)` enter a region of crossed electric and magnetic fields as shoen in Fig. If the electric field is `3.0xx10^(6)` Vm and the flux density of the magnetic field is 1.5 T, the electrons upon entering the region of the crossed fields will

Options

A. continue to travel undeflected in their original derection.
B. be deflected upward in the plane of the diagram
C. be deflected upward on the plane of the diagram
D. none of the above

Answer

C

Explanation

The ratio of electric force to magnetic force is:
`(F_e)/(F_B)=(qE)/(qvB)=(3xx10^(6))/(2.4xx10^(6)xx1.5)=(5)/(6)`
Now, magnetic force on beta particles acts downward, whereas electric force acts upward and both are in the plane of diagram. But since magnetic force is larger, so beta particles are deflected downward.