Light is something that we commonly experience throughout the day and even in the night. It can be produced naturally and artificially. Briefly, natural sources of light are the sun, stars, lightning and fires. On the other hand, artificial sources of light are man-made such as candles, light bulbs, and torchlights.
The light that we can see with our eyes is called visible light. It travels in a straight line from its point of origin but can also be reflected and refracted.
Reflection is the phenomenon of change in direction of visible light from a surface. If the surface is made of glass or polished metal (smooth and shiny) visible light will reflect at the same angle as it hits the surface. If the surface is rough and uneven like stone or wood, visible light will still reflect but not at the same angle as it hits the surface. The reflection of visible light allows us to see and estimate the size and distance of objects in our surroundings. For that purpose, reflection of visible light is used in creating periscopes so that navy crew can look from inside their submarines.
On the other hand, refraction is the phenomenon of visible light entering different mediums, like from air into water or from water into glass. As visible light travels through different mediums, it is forced to bend and slightly change its speed depending on the difference in density between the mediums it travels. This is a useful property of visible light in designing telescopes, eye lenses and microscopes that allow us to adjust the direction of visible light and enhance our field of vision.
In addition, the process of refracting white light at a certain angle reveals seven colours of visible light. They are red, orange, yellow, green, blue, indigo and violet. A rainbow is a common example of this phenomenon that occurs when sunlight is refracted through water droplets in the air. Each colour comes with different intensities – red is the brightest colour. A common use of this property of visible light is in traffic lights where red is the colour used as a stop sign so drivers are more alert to it. Visible light also gives us the pleasure of seeing our world in colour.
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