Magnetic Effects of Current and Magnetism Part 3

A proton is moving undeflected in a region of crossed electric and magnetic fields at a constant speed of 2×105ms−1. When the electric field is switched off, the proton moves along a circular path of radius 2 cm . The magnitude of electric field is x ×104N∕C. The value of x is _______. Take the mass of proton =1.6×10−27‌kg.