What did Isaac Newton believe light was composed of?

• A. Waves
• B. Particles
• C. Photons
• D. Atoms

Answer: (B)

Isaac Newton proposed that light is composed of particles, often referred to as "corpuscles." This idea was part of his broader theory of optics, which he developed in the 17th century. His particle theory of light was significant in explaining how light travels in straight lines and reflects off surfaces, which could be observed in various experiments such as the reflection of light in mirrors and the refraction of light through prisms.

Newton's particle theory also helped to lay the groundwork for the later development of physical optics. Although the wave theory of light gained prominence later, particularly through the work of scientists like Christiaan Huygens and, much later, Albert Einstein with the concept of photons, Newton's initial belief in the particle nature of light was a crucial development in the study of optics.