Answer:
Step-by-step explanation:
When a charged particle is moving in a straight line, means undeflected in a crossed magnetic and electric field, it means the net force on the charged particle is zero.
magnetic force is balanced by the electric force
q v B = q E
Where, q be the charge on the particle, v be the velocity, B be the strength of magnetic field, e be the strength of electric field.
So, B = E / v