Physics question magnetic field

Hi,
Please could I have some help on question bi on page 18 of this paper. Why wouldn’t the particle go straight because wouldn’t it also experience an equal and opposite electrical force downwards and magnetic force upwards?
Question: https://pmt.physicsandmathstutor.com/download/Physics/A-level/Past-Papers/CAIE/Paper-4/QP/November%202018%20(v1)%20QP.pdf
Thanks!

I just want to confirm that you are asking the question shown below:

Because your question "sounds" weird.

Yes that is the question, is there no electrical force experienced, isn’t it a charged particle?

Hi,
Please could I have some help on question bi on page 18 of this paper. Why wouldn’t the particle go straight because wouldn’t it also experience an equal and opposite electrical force downwards and magnetic force upwards?
Question: https://pmt.physicsandmathstutor.com/download/Physics/A-level/Past-Papers/CAIE/Paper-4/QP/November%202018%20(v1)%20QP.pdf
Thanks!

there will be a centripetal force acting on it, initially upwards (from Flemming's LHR)
There is no electric field
It will curve upwards then carry on in a straight line when it leaves the field
It will not gain kinetic energy as the force is perpendicular to its motion so does no work
It will therefore leave with the speed it came in, i.e. v

When you say it will gain no ke and leave the same velocity, is it because in centripetal acceleration, only the direction of velocity will change but magnitude is constant, even if there is acceleration? Thanks