stopped in an intersection at a red light, you are in the lane left of a semi truck. what should you look out for when the light turns green?

Select the best definition for wavelength. the height of an oscillating electromagnetic wave the rate at which electromagnetic waves oscillate. the distance between two crests of an electromagnetic wave. the oscillations of electric and magnetic fields select the best definition for frequency. the oscillations of electric and magnetic fields. the height of an oscillating electromagnetic wave. the distance between two crests of an electromagnetic wave. the rate at which electromagnetic waves oscillate

Why should the wavelength scale of spectroscope be calibrated

Iso need with this one really lost on it me on this