Education

# Light as Electromagnetic Wave: Properties of Light

What is light? What are properties of light? What kind of behavior it has? These are the common questions about light that must be answered to understand its behavior. Basically light is an electromagnetic radiation which has dual properties; wave and particle. According to wavelength, Electromagnetic spectrum can be divided into several parts, from which visible parts a region having wavelength range of 380 to 730 nm. It means we can only see radiations which have wavelength in this range. Our eyes distinguish these wavelengths as different colors. Light of a single wavelength is termed as mono-chromatic light. Each light color has a single wavelength, colors like pink, orange don’t lie in electromagnetic spectrum as they are made up of different colors.

However, light of all wavelengths of visible region, is recognized as white light by our eyes and if no wavelength in visible region is present then we see it as dark.

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### Properties of light

• Light is a form of energy and speed of lights is 3×108 m/s. since it is the maximum speed in universe thus it proves light as electromagnetic wave.
• Since it is an Electromagnetic radiation so don’t need any medium for passing through i.e. they can pass through vacuum.
• Its intensity can vary.
• Light carries both energy and information and no other object in universe can travel with the speed of light, if it consists of matter (even in smaller amount).
• Energy of light is given by E = hv, Where “v” is frequency of light and “h” is Plank’s constant.
• It consists of many colors.
• It can interact with matter.
• Dual nature of light: It has dual nature and behaves as both wave and particle.

• Light can reflect (return of light to the same medium from which it was made incident. Reflection happens when surface doesn’t absorb energy of light then bounces it off) and refract (it happens when light changes speed, if light slows down then it is refracted toward normal line and if it becomes faster then it is refracted away normal line) through some surface.
• Light undergoes dispersion when it is passed from prism. Prism divides light into seven colors according to their wavelength.
• When light is made incident on some transparent material, some of its energy reduces in form of heat and then it moves forward in that material with less energy and shows only the colors which are not absorbed. These transmitted wavelengths are called absorption colors.
• Polarization of light: Light can be polarized, it is a property of light in which light is restricted to move in one plane only and is called polarized light. However, normal light waves propagate in all directions perpendicular to its moving direction.

• Diffraction of light: Diffraction means slight bending of light as it passes about the edge of an object. How much light will bend? This thing depends upon relative size of opening and wavelength of light. If opening is of much larger size then wavelength of light then bending will be un-noticeable. However, it can be seen easily with naked eyes, if both have relevant value.

### What is silver lining around cloud or sun edges?

When light gets diffracted in atmosphere around atmospheric particles then diffracted light produce fringes of light or dark colored bands. These atmospheric particles are tiny droplets of water usually found in clouds. This formation shows how light (from either moon or sun) gets bent around tiny droplets in cloud.