Just asking ‘what is light energy’ opens you up to a flood of other questions trying to narrow down the context that you are asking the question in. In photometry, luminous energy is the perceived energy of light. It can also be defined as the electromagnetic radiation of visible light. Since light itself is energy, then another definition is relevant: light is nature’s way of transferring energy through space.

The speed of light is about 300,000 km/s. To put that in perspective, when you watch the sun set, it has actually been 10 minutes since that light left the Sun. Light energy is measured with two main sets of units: radiometry measures light power at all wavelengths and photometry measures light with wavelength weighted with respect to a standardized model of human brightness perception. Photometry is useful when measuring light intended for human use. The photometry units are different from most units because they take into account how the human eye responds to light. Based on this, two light sources which produce the same intensity of visible light do not necessarily appear equally bright. Light exerts a physical pressure on objects in its path. This is explained by the particle nature of light in which photons strike and transfer their momentum. Light pressure is equal to the power of the light beam divided by the speed of light. The effect of light pressure is negligible for everyday objects. For example, you can lift a coin with laser pointers, but it would take 1 billion of them to do it. Light pressure can cause asteroids to spin faster by working on them like wind pushing a windmill. That is why some scientist are researching solar sails to propel intersteller flight.

Definition Light Energy

Light is all around us. It has the ability to tan or burn our skins, it can be harnessed to melt metals, or heat our food. Light energy posed a huge challenge for scientist up to the 1950′s. Hopefully, in the future, we will be able to use light energy and solar wind to travel among the stars.

Light is a form of energy which our sense of sight can detect. It is made of electro-magnetic radiation and travels in a straight path. In everyday we use the word “light” for at least 10 times a day!! Have you ever think about the energy we get from the light. Light is all around us. It has the ability to tan or burn our skins, it can be harnessed to melt metals, or heat our food. Light energy posed a huge challenge for scientist up to the 1950′s.

Definition Light Energy

For our purposes we will use light to mean all of the frequencies of radiation, known as the electromagnetic spectrum or EMS. Light is always in motion and cannot be stored, so it is a kinetic type of energy.

You might say that light is essentially "pure" energy, since it theoretically has no mass. Light is simultaneously a wave and a particle. The higher the frequency, the more energy the light or electromagnetic radiation contains. The greater the frequency, the more energy each particle, called the photon.

Definition Light Energy

  • Light energy refers to the electromagnetic energy that is visible to the human eye.

  • Light energy is energy that travels in straight lines called rays that fan outward from the source of the light.

  • Light energy is made of electro-magnetic radiation and travels in a straight path.

  • Light energy is the energy that pervades the entire universe.  
    The majority of light-energy waves are non-visible and exist at different 
    wave frequencies than visible light.

  • Light travels in waves in bundles of energy called photons.


Important facts about light energy

  • It may seem that light from a bulb only extends outward a certain distance, and then stops. But light actually travels an infinite distance, and the distance it extends does not depend on the brightness of the bulb. Our eyes can only see light of certain brightness, therefore it is perceived to have stopped once its brightness is diminished.

  • Anytime light travels through a substance, even air, it changes direction. It may be a large change of direction (through lenses or water) or it may be a small change of direction.

  • Reflections may be more noticeable on shiny surfaces, but light is reflected from many surfaces, shiny and not. The colors that are reflected depend on the surface’s colors.


Important facts about light energy

  • When light passes through a prism, the colors that make up white light are separated and made visible to the human eye. Students may believe that the prism adds colors to the light.

  • The cornea on the front of the eye serves to focus the light entering the eye. It is further focused through the lens of the eye in order to form an image on the retina.

  • The pupil of the eye is not a black object or spot on the surface of the eye.It is an opening in the center of the iris. It helps control the amount of light entering the eye.


Steam energy


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