How fast does light travel?
Because light is found on the electromagnetic spectrum, light travels at the same speed as other electromagnetic waves, which, in a vacuum, is 299,792,458 m/s, or 186,282.4 mi/s. Except when performing experiments that need the exact velocity of light, this number is usually rounded up to 3 108 m/s (186,000 mi/s). Just like any other wave, light does slow down when it enters the Earth’s atmosphere.
One important thing to know about light is that it travels and behaves as waves. Light also has the character of a particle, but we’re going to just look at some basic stuff about light as a wave. All light travels in the form of waves at a speed of about 300,000 (300 thousand) kilometers per second in a vacuum such as space. That’s about 186,000 miles every second. That means light can travel almost eight times around the Earth in a second. That’s pretty fast! Light has slightly slower speeds when it travels through denser material such as a planet’s atmosphere or a piece of glass There are many different kinds of light besides the one you can see. What do you think is a good word to describe the light you see? Scientists often describe the light you can see as “visible” light. The entire range of different kinds of light including the ones the human eye cannot see is called the electromagnetic spectrum. Can you think of some other types of light besides visible light? You’ll be tryin
Video Transcript How Fast Does Light Travel? Hi, I’m Steve Jones and I’m going to tell you how fast light travels. Well, light itself is a form of electro-magnetic radiation. Now, electro-magnetic radiation, it, comes in many forms. And starting at one end, we have radio and then we have we have microwaves. And next to microwaves we have infrared and then we have visible radiation which we call light. And then we have ultraviolet and onto x-rays at this end. So we have many types of electro-magnetic radiation and the similarity between them is the speed. The speed of electro-magnetic radiation is always 3 X 10 8 m/s or 186,000 miles/sec or 300,000 km/sec in vacuo; in vacuo. That means in a vacuum. Of course if I actually ask light to travel through something like glass; glass is a good example; it would go down to 200,000 km/sec because it travels slower in transparent media. So if it’s in plastic, it would be about 250,00; in glass, 200,000 and so on. So the speed of light depends not
