Facts About Light

• 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.
• The currently accepted value is 299 792 km/s based on several measurements.
• 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.
• There are different colours of light because they are light waves which have different wavelengths. 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.
• 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.