A charged particle moving along the x-axis enters a uniform magnetic field pointing along the z-axis. Because of an electric field along the y-axis, the charge particle does not change velocity. What is the sign of this particle

Explanation:

Let the charge particle have charge equal to +q .

force due to electric field will be along the field that is along y - axis . To balance it force by magnetic force must be along   - y axis. ( negative of y axis )

force due to magnetic field = q ( v x B ) , v is velocity and B is magnetic field.

F = q ( v i x B k )  , ( velocity is along x direction and magnetic field is along z axis. )

= (Bqv) - j  

= - Bqv j

The force will be along - ve y - direction .

If we take charge as negative or - q

force due to electric field will be along - y axis .

magnetic force = F = -q ( v i x B k )

= +  Bqv j

magnetic force will be along  + y axis

So it is difficult to find out the nature of charge on the  particle from this experiment.

nah.   i'm just sleepy.

conservation of mass

mass before something happens = mass afterwards