Question

Find the condition under which the charged particles moving with different speeds in presence of electric and magnetic field vectors can be used to select charged particles of particular speed

Answer 1

Actually there is the formula through which moving uniformly charged particles can be selected under electric and mechanical field
velocity selectors v=E/B
here E represent electric field which defined as "the region or space around a charged particle whithin which it exert force on other objects" while B is representing the magnetic field.