the ultraviolet rays that cause sunburn are called UV-B rays, and have a wavelength of about 3.0 x 10^-7 m. What is the frequency of a UV-B ray?

Along wire carrying a 4.2 a current perpendicular to the xy-plane intersects the x-axis at x=−1.7cm. a second, parallel wire carrying a 3.0 a current intersects the x-axis at x=+1.7cm. part a at what point on the x-axis is the magnetic field zero if the two currents are in the same direction? express your answer to two significant figures and include the appropriate units.