Amy counts the wave crest traveling down a stretched string five wave crests pass amy in two seconds what is the frequency of the wave

In a 1.25-t magnetic field directed vertically upward, a particle having a charge of magnitude 8.50 mc and initially moving northward at 4.75 km> s is deflected toward the east. (a) what is the sign of the charge of this particle? make a sketch to illustrate how you found your answer. (b) find the magnetic force on the particle.