A positive charge q of mass m starts with velocity uî+wk̂ in fields B=Bk̂ and E=Ek̂. Let ω=qB/m. Which velocity vector is correct at time t?
Options

Question

A positive charge q of mass m starts with velocity uî+wk̂ in fields B=Bk̂ and E=Ek̂. Let ω=qB/m. Which velocity vector is correct at time t?

G1 Physics · Accepted Answer

For q>0 and B along +z, the transverse velocity rotates clockwise: vₓ=u cosωt and vᵧ=−u sinωt. The parallel electric field gives v along z=w+qEt/m.