Energy of electromagnetic radiation

An explanation of the many units used to describe the energy of electromagnetic radiation is provided in the following paper. 

Radiant Energy—The energy of electromagnetic radiation, such as radio waves, visible light, x and gamma rays. 

It follows that the x-axis in Figure 1.1 is an energy scale, since the frequency, wavelength and energy of electromagnetic radiation are interrelated ... 

The energy of electromagnetic radiation is inversely proportional to its wavelength. Since excitation of an electron for the tt — rr transition of ethylene occurs at a shorter wavelength (Amax = 170 nm) than that of cis, trans- 1,3-cyclooctadiene (Amax= 230 nm), the HOMO-LUMO energy difference in ethylene is greater. 

It turns out that electromagnetic waves exhibit properties of both waves and particles, or equally valid, electromagnetic waves are neither waves nor particles. This fundamental paradox is at the heart of quantum theory. You can perform experiments that unequivocally demonstrate light is definitely a wave. You can also perform experiments that unequivocally demonstrate light is definitely a particle. Nonetheless, there is one important relationship that allows the energy of electromagnetic radiation to be calculated if the frequency or wavelength is known ... 

Calculate the energy of electromagnetic radiation, and convert from wavelength to wavenumber and vice versa. 

Recall that the energy of electromagnetic radiation is E = hv, where h is Planck s constant and V is the freqnency. 

Energies of electromagnetic radiation relevant to photochemistry in different units... 

X-rays, for example, are much more energetic than rays of visible light. The frequencies of X-rays are on the order of 10 Hz, while those of visible light are on the order of 10 Hz. Since v = clX, the energy of electromagnetic radiation is inversely proportional to its... 

You will solve this problem by first calculating the energy needed for the magnetic excitation, E, by using the Planck-de Broglies formula for the energy of electromagnetic radiation ... 

The thermal energy of a hot source, such as the wall of a furnace at T, is converted into the energy of electromagnetic radiation waves. 

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