Light as a particle

Newton During the late 1600s, an important question emerged: Is light a swarm of particles or is it a wave in some pervasive medium through which ordinary matter freely moves? English physicist Sir Isaac Newton was a proponent of the particle theory.

Exploring colours Newton accomplished to give his own explanation for the nature of light. Light could be nothing more and nothing less than a succession of particles. Aristotle influenced science so much that after him all scientists used to believe that light was a separate entity, but they could not advance this idea.

White light, according to the view of his time, was uniform, or homogeneous, in content. Newton's first experiments with a prism called this view of white light into question. Passing a beam of sunlight through a prism, he observed that the beam spread out into a coloured band of light, called a spectrum.

Νewton describes a game with the prism

While others had undoubtedly performed similar experiments, Newton showed that the differences in colour were caused by differing degrees of a property he called refrangibility. prism Refrangibility is the ability of light rays to be refracted, or bent by a substance. For example, when a ray of violet light passes through a refracting medium such as glass, it bends more than does a ray of red light.

Newton concluded through experimentation that sunlight is a combination of all the colours of the spectrum and that the sunlight separates when passed through the prism because its component colours are of differing refrangibility. This property that Newton discovered actually depends directly on the wavelengths of the different components of sunlight. A refracting substance, such as a prism, will bend each wavelength of light by a different amount.