Force on a proton when they are moving inside the magnetic field is given by
so here while protons are going upwards we can say its direction of velocity is towards +Y and magnetic field is towards us which is along +Z direction so they will have force due to this motion.
As per above equation of force we can have direction of force which is along +X direction.
So here both proton will bend towards +X direction and start moving in curved path.
