Light is the external cause of sight. It produces the sensation of vision when it falls on the retina. Luminous objects like the sun emit their own light, while non-luminous objects like the moon are only visible because of light from luminous sources. Light propagates as electromagnetic waves and reflects off surfaces, with the angle of incidence equaling the angle of reflection.

1. Light Light is the external physical cause which produces the sensational of sight. When it falls on the retina of our eyes, it produces the sensation of vision and we can see the object