A particle of charge q and mass m starts moving from the origin under the action of an electric field E =E₀ i and B =B₀ i with a velocity v =v₀ j . The speed of the particle will become 5 2 v₀ after a time

Step-by-step solution

Here, E and B are acting along x -axis and v is along y -axis i.e. perpendicular to both E and B . Therefore, the path of charged particle is a helix with increasing speed. Speed of particle at time t is v= v_x^2+v_y^2 Here, v_y=v₀ ; v_x= q E₀ m t and v= 5 2 v₀ Putting values in ( i ) , we get t= m v₀ 2 q E₀