# Constant frequency for light waves?

• thursdaytbs
In summary, the frequency of red light in the air and in glass is constant, but the speed of light through different mediums can cause the wavelength to change, resulting in different colors. Frequency is directly proportional to wavelength, so as the wavelength decreases, the frequency stays the same. This is why the color of light is determined by its wavelength, not its frequency.
thursdaytbs
"what is the frequency of red light in the air? What is the frequency of red light in the glass?"

is the frequency of a light wave length constant? therefore, the answer would be the same?

The speed of a light wave through vacuum, air and glass is not the same due to some refraction effects. Try finding these speeds of light through those mediums and compute the frequency with those speeds.

thursdaytbs said:
"what is the frequency of red light in the air? What is the frequency of red light in the glass?"

is the frequency of a light wave length constant? therefore, the answer would be the same?
Correct, frequency never changes. When light slows down in high refractive index materials, only the wavelength changes.
Suppose you have light going from air to a material n=2. The velocity is going from x to 0.5x. Wavelength decreases at the same rate as the velocity (since wavelength and velocity are directly proportional), so if the original wavelength was $\lambda$, the new wavelength is 0.5$\lambda$. Frequency stays the same as it was before.

A way to remember might be to consider that if frequency were to change, then according to

$$E = h\nu$$

it would mean the energy changes as well. That would be a little too weird.

So wavelength is the critical factor which determine the colour of a wave but not other factors, such as frequency, right>?

That's right.

## 1. What is meant by "constant frequency" for light waves?

"Constant frequency" refers to the number of complete oscillations or cycles of a light wave that occur in a given amount of time. This frequency remains the same regardless of the medium through which the light wave is traveling.

## 2. How is the frequency of a light wave measured?

The frequency of a light wave is typically measured in Hertz (Hz), which is equal to one cycle per second. This can be measured using specialized equipment such as a spectrometer or by counting the number of wave peaks that pass a fixed point in a given time interval.

## 3. Does the color of light affect its frequency?

Yes, the color of light is directly related to its frequency. Red light, for example, has a lower frequency than blue light. This is because different colors of light have different wavelengths, and frequency is inversely proportional to wavelength.

## 4. Can the frequency of a light wave be changed?

Yes, the frequency of a light wave can be changed by altering the energy of the source producing the light. For example, when an object heats up, it emits radiation with a higher frequency, causing the color to change from red to orange to yellow and eventually to blue as the temperature increases.

## 5. What is the relationship between frequency and energy in light waves?

The frequency of a light wave is directly proportional to its energy. This means that as the frequency increases, so does the energy. This relationship is described by the equation E=hf, where E is energy, h is Planck's constant, and f is frequency. This relationship is important in understanding how light interacts with matter, as higher frequency light can have more energy and therefore create more significant effects.

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