An alpha particle, which is a helium nucleus, has a mass of 6.64 x 10-27 kg. it is traveling horizontally at 42.3 km/s when it enters a uniform, vertical 1.60 t magnetic field. what is the diameter of the path followed by the alpha particle?
0.208 mm
1.01 mm
0.878 mm
0.354 mm

Edit: You do mean Ridge?

Rocks near Mid-Ocean Ridge are younger than rocks near the trenches.

Seismic data shows oceanic crust is sinking into the mantle at the trenches.

Matching bands of magnetic rock are found on either side of the Ridge. Earth's magnetic fields change these bands over time.