Red and Blue Light Absorption

Question

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Answer 1

So let's look at the four options. Option A shows the excitation from energy level 1 to 2. Option B shows the excitation from energy 1 to 3. Option C shows the relaxation from 3 to 1, and Option D shows the relaxation from 2 to 1. First, we can talk about the directions of the arrows. When an electron relaxes from a higher energy level to a lower one, that energy has to go somewhere. In most cases, this leads to the emission of a photon. When an electron is excited from a lower energy level to a higher one, it received energy, in our case, from a photon striking the electron and being absorbed. Next, we can talk about the magnitudes. Jumping/Dropping from energy levels 1 and 3 have a larger magnitude than jumping/dropping from levels 1 and 2. This means that the amount of energy released/absorbed is higher. One important thing to note is that the energy of a photon is inversely related to its wavelength. Since red light has a larger wavelength than blue light, it has lower energy. Since we need the arrow to go up, and the arrow to be the smaller of the two, it can only be option A. If you need anymore clarification, please let me know!