Question

1. discuss the way in which einstein utilized plancks quantum concept to explain the photoelectric effect.

Explanation:

Planck proposed that energy is quantized, \( E = h
u \) (where \( h \) is Planck's constant and \(
u \) is frequency). Einstein extended this to light, considering light as composed of photons. For the photoelectric effect, when a photon (with energy \( E = h
u \)) hits a metal surface:

• If \( h

u\geq W_0 \) (work - function of the metal), an electron is ejected.

• The maximum kinetic energy of the ejected electron \( K_{max}=h

u - W_0 \). This explains why there is a threshold frequency (when \( h
u = W_0 \), \( K_{max} = 0 \)) and why the kinetic energy of electrons depends on frequency (not intensity, as intensity only affects the number of photons/electrons, not their energy per electron).

Answer:

Einstein used Planck's quantum concept (\( E = h
u \)) by considering light as photons. For the photoelectric effect, he proposed \( K_{max}=h
u - W_0 \), explaining the threshold frequency and the frequency - dependence of electron kinetic energy.