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"Sometimes the idea of the quantum is compared to the units we use for money. A dollar can be divided into smaller units, where the cent is the smallest possible unit."

A question I came across in a textbook. Given that their Planck formula is $E=nhf$, how is the analogy incorrect?

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Were you able to rule out any of the three factors as key to the question? – WillO Aug 4 '15 at 0:57

For example, when you are looking at the photon emitted from an electron going from energy level n=2 to n=1, the photon has a discrete energy and all photons that do this transition will have the same energy. However, if the photon passes from different energy levels (say n=3 to n=1), it will have a different energy. Both photons have discrete energies; however, they have different energy values.

In that was they are discrete, but have different values. 1 cent pieces are discrete, but all have the same value.

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