The phenomenon of Newton's rings, named after Isaac Newton, is an interference pattern caused by the reflection of light between two surfaces - a spherical surface and an adjacent flat surface. When viewed with monochromatic light, it appears as a series of concentric, alternating light and dark rings centered at the point of contact between the two surfaces. Using this apparatus, students can observe the phenomenon of equal-thickness interference. By measuring interference fringe separation, curvature of the spherical surface can be calculated.