amazing facts about light 10th cbse

Top 45 Amazing Facts About Light | Amazing Facts 4U

1. Light energy is the only energy visible to the human eye. Light rays have different colors due to differing wavelengths.
2. Light energy is made of electromagnetic radiation. A light wave consists of energy in the form of electric and magnetic fields. The fields vibrate at right angles to the direction of movement of the wave, and at right angles to each other.
3. Red light has the longest wavelength while violet light has the shortest wavelength. Scientists study the properties and behaviors of light in a branch of physics known as optics.
4. Obviously, the biggest source of light energy is Sun comes from the Sun. It transfers an incredible amount of energy to our planet in spite of being millions of miles away.
5. Without the light energy from the Sun, humans and all other living creatures can’t survive. Plants absorb light energy to make food. Without sunlight, plants would not survive. Without light energy from Sun, our planet would be too cold for us to continue living!
6. The wavelengths of the light that most people can see ranges from 400 to 700 billionths of a meter. Infrared and Ultra Violet rays are found just beyond visible spectrum.
7. The speed of light is approximately 300,000 kilometers per second which is faster than the speed of anything else! The speed of light changes when travelling through different objects.
8. Unlike sound waves or water waves, light does not need any matter or material to carry its energy along. Thus, light can travel through a vacuum.
9. Light takes 1.25 seconds to get from the Earth to the Moon and about 8 minutes from the Sun to earth. Really long distances can be measured in light year which is the distance that light can travel in a year.
10. A ‘jiffy’ is an actual unit of time. It is the time it takes for light to travel one cm in a vacuum, which is about 33.3564 picoseconds.
11. 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, can’t see diminished brightness giving the impression that light has stopped.
12. Amazingly light energy is always moving and can therefore not be stored.
13. Humans and animals would be unable to see anything without light energy. It’s because of light that we have the sense of sight.
14. 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.
15. Besides sunlight, light is emitted by hot objects such as light bulbs, and Lasers. A laser produces an incredibly powerful, concentrated form of light. This is the result of light waves bouncing back and forth between two mirrors to build up energy before being released as a narrow powerful beam which can travel long distance without losing quality.
16. Amazingly space is dark because light is only visible when it has an object from which it can bounce off to be visible.
17. Light energy travels in a straight line passing through transparent materials like glass and bouncing off other materials which are not transparent. The light rays can also bend with change of medium which is known as refraction.
18. Light waves travel out from their source in straight lines called rays. Rays do not curve around corners, so when they hit an opaque object, they are blocked from reaching the other side of that object. Shadow is the area where light is blocked.
19. The light energy from the sun provides our Earth with heat and controls its temperatures.
20. If our skin is over-exposed to sunlight it can burn and chronic exposure can lead to skin cancer. It can also damage our eyes if we look directly at the Sun.
21. Light energy reflects off surfaces. Moonlight is not produced directly by the moon. Actually, the Sun shines on the moon and the light is reflected back to Earth!
22. Light energy can be converted into other types of energy such as solar and chemical energy. During photosynthesis, plants use light energy to create chemical energy wherein carbon dioxide is converted to food.
23. Amazingly every second around 100 lightning bolts strike the Earth. In fact, lightning kills 1000 people every year in the world.
24. Red, green and blue (RGB) are the primary colors of light. Mixing them in various ways will make all other colors, including white.
25. 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 colors, and the second refraction increases the separation. The resultant refraction in billions of drops in the clouds result in a rainbow.
26. In fact, there are millions of colours in a rainbow. We classify them into 7 main groups of colours that our eyes can see.
27. Isaac Newton observed for the first time that a thin beam of sunlight hitting a glass prism on an angle creates a band of visible rainbow colours because different colours travel through glass at different speeds, causing them to refract at different angles and separate from each other.
28. Mediums are given a refractive index to describe by how much they slow the movement of light. Glass has a refractive index of 1.5, meaning that lights travels through it at around 1/1.5 speed (200,000 kilometres per second). The refractive index of water is 1.3 while the refractive index of air is 1.0003.
29. Refraction can make things look closer than they really are. The difference in speed between light traveling through water and through air means that, from the surface, a 4-meter pool appears to be just 3-meter deep.
30. More than half of the visible light spectrum is absorbed within 3 feet of the ocean’s surface; at a depth of 10 meters, less than 20% of the light that entered at the surface is still visible; by 100 meters, this percentage drops to 0.5%.
31. When light energy passes through a prism, the colors that make up white light are separated and made visible to the human eye (VIBGYOR).
32. The light bulb was invented in 1879 by Thomas Alva Edison.
33. Amazingly when you turn on a light bulb only 10 % of the electricity used is turned into light, the other 90 % is wasted as heat.
34. Low energy light bulbs last on average up to 12 times longer than traditional fluorescent bulbs.
35. UV lights having shortest wave lengths 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 and animals have the ability to see it
36. About 20% of the human population is estimated to be affected by a so-called “photic sneeze reflex,” a heritable condition that results in sneezing when the person is exposed to bright light.
37. The light from the dazzling northern lights is the result of solar wind which during solar flares reach Earth’s atmosphere interacting with particles of oxygen atoms, causing them to emit stunning green lights.
38. The Hubble telescope has detected the existence of countless galaxies receding from our point in space at speeds in excess of the speed of light. This massive expansion also means that there are some galaxies whose light we’ll never see.
39. In fact, at depths of over 1000 meters, a region of the ocean dubbed the “aphotic zone” there is no detectable light whatsoever. As a result, the largest source of light in the Earth’s oceans actually emanates from animals residing in its depths which are bio luminescent (About 80 to 90%).
40. All living creatures including humans produce some amount of light as a result of metabolic biochemical reactions. This light is thousand times weaker than what human eye can perceive.
41. All humans have the ability to see ultraviolet light, but it is passively filtered out by the eye’s lens. Patients who undergo surgery to remove the lens can detect ultraviolet light.
42. Peacock feathers are actually brown, but have microscopic structures that interfere with light that make the bright iridescence.
43. In 1999, Harvard physicist Lene Hau was able to slow down light to 17 meters per second and in 2001, was able to stop light completely.
44. Amazingly there is a deep-sea fish named Stoplight Loosejaw that takes advantage of the fact that fish can’t see red light, and illuminates its prey with a beam of red bio luminescence so it can hunt with an effectively invisible beam of light.
45. According to English law, the “Right to light” states that the owner of a building with windows who has received natural daylight for 20 years or more is entitled to forbid any construction or other obstruction that would deprive him or her of that illumination.