Question

According to the quantum theory of light, the energy of the light is carried in discrete units called
A) Alpha particle
B) Photoelectrons
C) Protons
D) Photons

Answer 1

Hint: According to EM wave physics, light travels in the form of an energy packet across space. The intensity (i.e. the energy generated per unit area and time) is directly proportional to the square of the amplitude of the electrical field generated. Now, the energy received between the transmitter and receiver is not in wave form but in form of tiny energy packets.

Complete step by step solution:
The particles that forms the discrete units of energy are neutral in charge as photons have no mass but constitute an energy of \[E\text{ }=\text{ }hf\text{ }=\text{ }\dfrac{hc}{\lambda }\]. Here, the value of h is the Planck’s constant which is \[6.626\times {{10}^{-34}}js\]
The energy generated by the photons is inversely proportional to the wavelength of the electromagnetic wave. The energy is generated more if the wavelength is short and the vice versa for lesser energy generation.
Photons can be either created or destroyed at the same time. When a transmitter emits electromagnetic waves, photons are produced. When photons strike a mass or object, they may either take and transfer that energy to the atoms and molecules. Therefore, according to the quantum theory of light, the energy of light is transferred in the form of photons.

Note:Both Protons and alpha particles are positive in nature with one and two positive charges respectively, whereas photoelectrons are particles generated when energy or photon is given to an atom so that the electrons becomes or jumps to an excited state. Hence, only protons are left that can be considered a neutral energy particle.