Thursday, September 18, 2008

Fundamentals: Quantum explanation

When light of frequency f is incident on the photoelectric surface , no photoelectrons are emitted (no photocurrent recorded) eventhough light of very high intensity is used. Explain.
To explain using quantum theory is to use photon energy E= hf.

1. The photon energy is insufficient as it is smaller than the work function and hence no emission is possible.
2. Increasing the intensity only increases the rate of photons but the energy of photons remains the same as E = hf. Unless f is increased no emission is possible.

Point no. 1 mention photon energy which implies light is a packet of energy (Particle or quantum concept)
Point no. 2 actually refute wave theory because increasing intensity increases the energy received by the photoelectric surface but yet no emission is possible .