If at a particular instant and at a certain point in space the electric field is in the x-direction and has a magnitude of 4.10 V/m , what is the magnitude of the magnetic field of the wave at this same point in space and instant in time

The electric field between square plates of a parallel-plate capacitor has magnitude e. the potential across the plates is maintained with constant voltage by a battery as they are pulled apart to twice their original separation, which is small compared to the dimensions of the plates. the magnitude of the electric field between the plates is now equal to a)e b)e/4 c)e/2 d)4e e)2e