In Newtonian physics, light is explained using a particle model known as the corpuscular theory of light. According to this theory, light is composed of tiny particles called "corpuscles" or "particles of light" that are emitted from a light source and travel in straight lines. These particles are considered to have mass and momentum.
Isaac Newton proposed this corpuscular theory of light in the 17th century, primarily to explain the behavior of light in terms of particles. Newton suggested that these corpuscles are emitted by a light source, and they travel in a straight line until they encounter an obstacle or are reflected or refracted at an interface.
Newton's theory could account for certain phenomena, such as the rectilinear propagation of light (traveling in straight lines) and the reflection of light from a mirror. However, the corpuscular theory faced challenges in explaining other phenomena, such as diffraction and interference, which are more effectively described using a wave model of light.
It's important to note that later experiments and observations, such as Thomas Young's double-slit experiment in the early 19th century, demonstrated the wave-like nature of light, leading to the development of the wave theory of light and the subsequent acceptance of the wave-particle duality of light in quantum physics. The wave theory, later refined by James Clerk Maxwell's electromagnetic theory, provided a more comprehensive and accurate description of light phenomena than the Newtonian corpuscular theory.