A positively charged particle with an initial velocity of 6.0 km/s in the positive x direction enters a region of uniform electric and magnetic fields. The electric field has the strength of 12 kV/m and is directed in the positive y direction.

a) Determine the strength and direction for the magnetic field such that the particle passes through undeflected.

b) What magnetic field (magnitude and direction) is needed if the particle was negatively charged? Explain your answer.

Show the work leading to the final formula/result