Acopper wire has a diameter of 1.02mm and carries
a constant current of 1.67a. if the density of
free electrons in copper is 8.5 x10 to the power 28 per meter cube. calculate
the current density and drift velocity of the electrons

Ultraviolet radiation is dangerous because it has a high enough energy to damage skin cells. what is the best explanation of the relationship between wavelength and wave energy? a) wave energy is related only to frequency, not wavelength. b) longer wavelengths have lower frequencies but higher energy. c) the shorter the wavelength, the lower the frequency and the higher the energy. d) the shorter the wavelength, the higher the frequency and the higher the energy.