Light Energy Facts

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Light Energy Facts

Our universe and our world are awash in light. This article about Light Energy helps students explore the nature of light, the movement of light, natural and man-made sources of light, and the special behaviors and properties of light. More interesting and important facts about light energy are explained here.

  • The speed of light is generally rounded down to 186,000 miles per second. In exact terms it is 299,792,458 m/s (metres per second – that is equal to 186, 287.49 miles per second).

  • It takes 8 minutes 17 seconds for light to travel from the Sun’s surface to the Earth.

  • Every second around 100 lightning bolts strike the Earth.

  • Every year lightning kills 1000 people.

  • Red, green and blue are the primary colours of light. Mixing them in various ways will make all other colours, including white.

  • 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.

  • The bending of light as it passes from one transparent substance to another, like air to water, is called refraction.

  • When sunlight is intercepted by a drop of water in the atmosphere, some of the light refracts into the drop, reflects from the drop’s inner surface, and then refracts out of the drop. The first refraction separates the sunlight into its component colours, and the second refraction increases the separation. The result is a rainbow.

  • During photosynthesis, plants use light energy to create chemical energy.

  • UV lights are often used by forensic scientists to see details that are not seen by the naked eye.

  • Although humans cannot see UV light, some insects have the ability to see it

  • The speed of light changes when travelling through different objects.

  • Light is a type of electromagnetic energy.

  • Light is made of tiny photons which contain lots of energy.

  • The intensity of photons is dependent upon the amount of energy they contain.

  • Light energy is always moving and can therefore not be stored.

  • The reason we see different colours of light is because each colour has a different wavelength.

  • Red light has the longest wavelength while violet light has the shortest wavelength.

  • The light bulb was invented in 1879 by Thomas Alva Edison.

  • When you turn on a light bulb only 10 per cent of the electricity used is turned into light, the other 90 per cent is wasted as heat.

  • Low energy light bulbs last on average up to 12 times longer than traditional fluorescent bulbs.

  • A heavy coat of dust can block up to half of the light.

Important facts about light energy

  • It may seem that light energy from a bulb only extends outward a certain distance, and then stops. But light energy 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 energy 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 energy is reflected from many surfaces, shiny and not. The colours that are reflected depend on the surface’s colours.

  • When light energy passes through a prism, the colours that make up white light are separated and made visible to the human eye. Students may believe that the prism adds colours 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 centre of the iris. It helps control the amount of light entering the eye.

  • We may be familiar with the seven colours of a rainbow (red, orange, yellow, green, blue, indigo, and violet). In fact, there are millions of colours in a rainbow. We classify them into seven main groups of colours that our eyes can see.

  • A white light energy source, such as an incandescent or fluorescent bulb, produces light made up of all colours. It only appears white because the colours are blended. When filters are added, the light appears a different colour, but filters do not add colour to the light. Actually, like other filtering materials, colour filters allow only certain colours of light to pass through, and they absorb or reflect the others.