Einstein showed what could be explained if photons carried quantized amounts of energy?

Question

Ivy Allen · Accepted Answer

The photoelectric effect (the spontaneous emission of electrons when illuminated by light of a sufficiently high frequency.)

This phenomenon was known, but not understood, until Einstein’s paper in 1905 (his “marvellous year”) and contributed to the ultra-violet catastrophe being resolved (see here: https://tutor.hix.ai) It predicted that photoelectrons would only be emitted from a negatively charged plate when the energy (given by #E = h.f#) exceeded the work function (#phi#) of that particular metal. More details (perhaps more than you want) here: https://tutor.hix.ai This marked the beginning of the most successful and accurate theory in the history of physics: quantum theory. Interestingly, when physicists working in the field were asked to rate their understanding of quantum theory (n=129), slightly more than one-third preferred the Copenhagen interpretation, a smaller percentage accepted the Many Worlds Hypothesis, and nearly a third were happy to admit that they did not really understand it well enough to make a decision. The idea that we are all lifelong learners appeals to me!

Christopher Ales · Answer

undefined Photons carrying quantized amounts of energy could explain the photoelectric effect, as demonstrated by Einstein.

HIX Tutor · Answer

undefined Einstein demonstrated that if photons carried quantized amounts of energy, it could explain the phenomenon known as the photoelectric effect. Here's a step-by-step explanation:

1. The photoelectric effect is the emission of electrons from a material when light shines on it. However, scientists were puzzled because they expected that increasing the intensity (brightness) of light would increase the energy of the emitted electrons.

2. Einstein proposed that light energy is carried in discrete packets called photons, and each photon carries a specific amount of energy. This idea is known as quantization.

3. According to Einstein, for the photoelectric effect to occur, an incoming photon must transfer all of its energy to a single electron in the material. If the photon's energy exceeds the binding energy of the electrons, the electron can escape from the material.

4. The energy of a photon (E) is related to its frequency (f) through the equation E = hf, where h is a constant called Planck's constant.

5. Based on Einstein's theory, the energy of the emitted electrons depends on the frequency of the incident light. Increasing the intensity of the light source would increase the number of photons, not their energy.

6. This explained why increasing the intensity of light does not increase the energy of the emitted electrons in the photoelectric effect. Only increasing the frequency (or energy) of the photons can do that.

In summary, Einstein's proposal that photons carry quantized amounts of energy provided a satisfactory explanation for the photoelectric effect, where the energy of emitted electrons depends on the frequency of the incident light, rather than its intensity.