Force exerted by a uniform electric field on an electron having mass m1 and proton of mass m2 are represented as F1 and F2 are related as 

Dear Student

THe force on charged particle having charge q in an electric field E can be given as
F = qE

The proton and electron have equal and opposite charge therefore force  when they are placed in uniform electric field is
F₁=(-q)E.
F₂ = qE
So when they are placed in uniform electric field, the magnitude of forces are equal but direction is opposite.
So
F₁ = -F₂
Regards