A moving proton enters the region between the plates from the left, as shown in the figure below.
The proton is deflected by the electric field. On the figure above, draw a line to show the path of the proton as it moves through and out of the region of the electric field.
A helium nucleus 
now enters the region of the electric field along the same initial path as the proton and travelling at the same initial speed. State and explain how the final speed of the helium nucleus compares with the final speed of the proton after leaving the region of the electric field.
