Maxwell's electromagnetic wave theory and Planck's quantum theory are both fundamental theories in physics, but they describe different aspects of the behavior of light and other electromagnetic waves.
Maxwell's electromagnetic wave theory, developed by James Clerk Maxwell in the 19th century, describes how electromagnetic waves propagate through space. According to this theory, light is an electromagnetic wave consisting of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of wave propagation. Maxwell's equations mathematically describe the relationship between electric and magnetic fields and how they change over time, providing a comprehensive framework for understanding phenomena such as reflection, refraction, diffraction, and interference of light.
On the other hand, Planck's quantum theory, formulated by Max Planck in the early 20th century, revolutionized our understanding of the behavior of light and other forms of electromagnetic radiation at the atomic and subatomic level. Planck proposed that energy is quantized, meaning it can only exist in discrete packets or "quanta." In the case of light, these quanta are called photons. Planck's theory introduced the concept of the photon as the fundamental unit of electromagnetic radiation. According to quantum theory, the energy of a photon is proportional to its frequency, and the energy is quantized in multiples of the Planck constant (h). This theory provided an explanation for phenomena that could not be explained by classical physics, such as the photoelectric effect and the blackbody radiation spectrum.
In summary, Maxwell's electromagnetic wave theory focuses on the classical behavior of electromagnetic waves, describing their propagation and interaction with matter. Planck's quantum theory, on the other hand, introduced the concept of quantized energy and explained the discrete nature of light at the atomic level, providing a framework for understanding phenomena that could not be explained by classical physics alone. Both theories are crucial in modern physics, and they are complementary in explaining different aspects of the behavior of light and other electromagnetic waves.