Answer:
B = 1.37 mT
Step-by-step explanation:
Given that,
The magnitude of the electric field, E = 480 N/C
The speed of the proton,
We need to find the magnitude of the magnetic field. In a velocity selector, the electric field is balanced by the magnetic field. So,
Where
B is the magnetic field
So, the magnetic field is equal to 1.37 mT.