I am stuck on a electromagnetic homework question. The question asks for the B field on a perfectly conducting plane that is grounded. I am confused because the point being asked for is on a grounded plane, so should the B field be zero becaue the potential is 0? I have attached the image of the homework problem. Any ideas would be help and very much appreciated.

 

If current is moving, a magnetic field will be generated.

The magnetic field doesn't depend on potential.