How to calculate the velocity and radius of curvature of a charged particle in a perpendicular magnetic and parallel electric field?

If I have a charged particle come from a point velocity V1 where there is a uniform electric field parallel to the motion of the particle which accelerates it and a magnetic field perpendicular to both velocity and electric field, I have to find velocity when the particle becomes perpendicular to both fields( since the magnetic field bents the trajectory of the particle it will become perpendicular to both fields )to know velocity at that point I have find distance traveled or I should know the extended radius ( extended by electric field ) .with formula r = mv÷ qB I can find the radius R1 but when the particle becomes perpendicular to both forces this radius will be extended and become R2 as the electric field will accelerate the particle and so v will increase which inturn increases the radius Is there any formula where I could apply both electric field and magnetic field into formula and find R2. I

• Note that we use MathJax to typeset mathematics; you can find a good tutorial here. – Emilio Pisanty Aug 9 at 17:25
• Thanks. I am new to physics stack and thank you, Emilio, for the information. – Abraham manoj Aug 10 at 4:17