Dual Nature Of Radiation And Matter

- Some questions are often misinterpreted by the students. Let's explore them!
Some questions are asked based on characteristics of photon. Students get confused here because the properties of photon are not totally similar to that of ordinary particle. For illustration, an ordinary particle has mass but a photon has no mass. Therefore it is important to understand the properties of photon.
The energy and momentum of a photon are related as
The photon behaves like a particle.
Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
Assertion is correct but Reason is incorrect
Both Assertion and Reason are incorrect
A classic problem is to count the number of photons normally striking per unit area in a photoelectric effect. The pro tip here is the intensity of radiation is related to the number of photons. There if we know intensity or power we can calculate the number of photons.
Sometimes students mix up the energy of incident photons and the kinetic energy of photoelectrons. Remember that the photoelectrons are coming out of the surface because of the striking of incident photons. Therefore it is obvious that the kinetic energy of photoelectrons must less that the energy of incident photons.
Questions are asked based on temperature dependence of de Broglie wavelength. Students may be clueless to establish the relationship. But a particle can have energy due to temperature (thermal energy). This is the same energy of the associate matter wave. Now finding the de Broglie wavelength when energy is known is a trivial calculation.
Students may wonder knowing the de-Broglie wavelength of a projectile particle. But is technically possible. a projectile has its own momentum. Therefore, using de Broglie hypothesis one can easily calculate the de Broglie wavelength.