: a theory in physics: light is transmitted from luminous bodies to the eye and other objects by an undulatory movement. — called also undulatory theory.

Christian Huygens

Huygens’ Principle. Huygens’s Principle states that every point on a wavefront is a source of wavelets, which spread forward at the same speed.

Sir Isaac Newton was a strong advocate of the particle nature of light. But, the Dutch physicist, Christiaan Huygens believed that light was made up of waves vibrating up and down perpendicular to the direction of the wave propagation, and therefore formulated a way of visualizing wave propagation.

The four theories of Light

• Newton’s corpuscular theory.
• Huygen’s wave theory.
• Maxwell’s electro magnetic wave theory.
• Planck’s quantum theory.

Wave-Particle Duality of Light. Quantum theory tells us that both light and matter consists of tiny particles which have wavelike properties associated with them. Light is composed of particles called photons, and matter is composed of particles called electrons, protons, neutrons.

A shadow is the dark shape made when something blocks light from a light source like the sun, a flashlight, or campfire. Light travels in a straight line but stops when something blocks it, creating a shadow, which may be short or tall depending on the angle of the light source.

In simple terms, natural light is light that is generated naturally, the common source of which is the Sun. This is as opposed to artificial light, which is typically produced by electrical appliances such as lamps.

Natural light photography uses the sun as a light source. The available light from the sun varies with the time of day. This stands in contrast to middle-of-the-day photography, where the direct sun can provide overly harsh light on an object or a subject’s face.

A few examples of natural light sources include the Sun, stars and candles. A few examples of artificial light sources include light bulbs, lamp posts and televisions. Without light sources we could not see the world around us, however, not every object we see is a light source.

the sun

the Sun