Does the speed of light changes with diferent colors?
Yes, when passing through a medium such as air, or glass, light slows down by a ratio called the refractive index, and it varies slightly depending on the wavelength of the light. When light travels through a vacuum it all moves at the same speed, 299792458 m/s, regardless of wavelength. However, when light passes through a medium, such as a prism, different wavelengths travel at different speeds, which is why the different colors emerge from a prism at different angles.
Why does light travel at different speeds in the same medium according to wavelength?
Imagine you can walk along a pavement at 4mph. When the pavement is empty, it takes you an hour to travel four miles. But when the pavement is crowded, you're dodging around people and bumping into them. You're still walking at 4mph, but it takes you an hour and a half to travel the four miles. And if you're a little old lady with short little steps walking at 4mph, you're held up more than if you're a big guy with long strides walking at 4mph. Now let's look at your questions again:But I wonder why their speeds differ in any other medium?Because the light interacts with the material, and those interactions are wavelength dependent.And why Red light travels faster while it has less energy than blue light?Because the light interacts with the material, and those interactions are wavelength dependent! Hope this helped you !!
If different colors of light have different speed & wavelength then why do we see it as a white beam of light & not as separated frequencies of light?
Light travels at the same speed in vacuum. And this speed do not depends on the wavelength of the light because as wavelength changes frequency changes accordingly.Even in air speed of different wavelengths of light is same and that is the reason that we don,t observe spectrum in air.But in some mediums like glass different wavelength travels at different speed and due to that refractive index of glass is different for different frequencies.And when light travels from one medium to other medium it gets bend and the angle of refraction dependa on the refractive index of mediun byAs refractive index of different frequency are different so they bends at different angles and we see different colors.
Do different wavelengths of light (as colors) travel at the same speed?
The speed of light in vacuum is constant and does not depend on characteristics of the wave (e.g. its frequency, polarization, etc). In other words, in vacuum blue and red colored light travel at the same speed c.The propagation of light in a medium involves complex interactions between the wave and the material through which it travels. This makes the speed of light through the medium dependent on multiple factors which include the frequency (other example factors being refraction index of the material, polarization of the wave, its intensity and direction).The phenomenon due to which the speed of a wave depends on its frequency is known as dispersion and is the reason why prism and water droplets separate white light into a rainbow.
Why dispersion of light do not occur in vacuum or air medium?
A white light is formed of 7 colours viz. violet indigo blue green yellow orange red or VIBGYOR. When a white light is sent through a prism ,due to its greater density than air, it slows down the velocity of the white light. But as a white light is formed of 7 colours so each colour moves with a different velocity which results in dispersion as one colour moves faster than the other in the prism. In air this density required to cause dispersion is very low hence almost all the colours move with same velocity. A light( white light) is a form of energy.When this light passes through air this light is not absorbed or very minimally absorbed i.e., all the components of this white light are equally scattered and thus makes us to see a white light rather than a particular colour. In the prism all the components of light are not equally absorbed. Some are absorbed more some are less. Some remain absorbed for longer period of time and some for lesser period of time before they are scattered.Due to these differences the dispersion occurs in a prism and not in air.
Do light waves of different colors all travel at the same speed in glass?
No. They travel at different speeds Glass has a bunch of molecules/Atoms that makes it glass. These atoms are in the way of traveling light. Higer energy light has an easier time getting throught the glass. EX: A big football player (higher energy) can run right through and destroy a group of guys from the chess club. A 4 year old school girl (less energy) will find it difficult to break through a defening group of chess geeks. The girl will eventual push through some but ..she will be slower at getting through. Light energy = h*frequency. The wavelength is what determines the color of visible light. NOTE: What is actuallly happening with light though is that most of the light particles are being absorbed and then reemitted by the atoms. That process takes time. In other words the light slows down. It must then be the case that lower energy light (lower frequency) has a higher chance of being absorbed by the atoms. EX: If you move slower someone punching you has a easier time hitting you. It also may be the case that glass electrons have electron energy levels that have a larger range of energy in the range of lower frequency light. Therefore more of it is aborbed than higher frequncy light
Why is the speed of all the colours of white light same in vacuum? This question was asked in ICSE 2018 physics examination.
Speed of light in medium = speed of light in vacuum / refractive Index of the medium. Let’s call this equation #1Refractive Index of a medium = wavelength of light in vacuum / wavelength of light in medium. Let’s call this equation #2By comparison of equation #1 & #2 you can see that. Speed of light in medium is directly proportional to wavelength of light in medium.Refractive Index in vacuum is 1 by equation #2 for all wavelength of light so all have same speed in vacuum.Refractive Index is different on medium and depends on the wavelength of each color hence the speed of color in different medium is different.I hope this answers your question
Why do all colors of light travel with the same speed in the air but not other media?
The speed is only constant for all frequencies in a perfect vacuum.As soon as you are not in a vacuum there are interactions between the light and the matter the light is passing through (or particles an individual photon interacts with) which are dependent on frequency.Ultimately, the phase velocity is what is affected.This is most obvious when the material is optically dense, such as glass.This video is worth watching if you want more information on the concepts. (notwithstanding the Atlas of Creation book behind him, I can vouch for the credibility of the answers he gives)