An 18,000-watt radio station transmits at 680 khz. Calculate the energy of a single photon at the transmitted frequency.
1) 4.5 x 10⁻²⁸ j/photon
2) 1.2 x 10⁻²⁹ j/photon
3) 4.5 x 10⁻³¹ j/photon