I attached the physics problem below

Find the magnetic field a distance r from the center of a long wire that has radius a and carries a uniform current per unit area j in the positive z direction.

Aphase diagram assumes is kept constant.

3. a particle with initial velocity v⃗ 0=(5.85×103m/s)j^ enters a region of uniform electric and magnetic fields. the magnetic field in the region is b⃗ =−(1.35t)k^. you can ignore the weight of the particle. a. calculate the magnitude of the electric field in the region if the particle is to pass through undeflected, for a particle of charge +0.640 nc.