# Answer "What Does C=Vλ Mean? Find Energy of Photon

• zeromodz
In summary: So, in summary, the equation C = Vλ represents the relationship between the speed of light, frequency, and wavelength. To find the speed of frequency, you can use the formula v = c/λ, where c is the speed of light and λ is the wavelength. To find the energy of a photon, you can use the formula E = hc/λ, where h is Planck's constant and c is the speed of light. Alternatively, you can use the simplified formula E = 1240eV x nm/λ, where λ is in nanometers.
zeromodz
Okay, I just need to grasp what the equation C = Vλ means
.
Correct me if I am wrong.
c = speed of light
v = speed of frequency
λ = wavelength

So if I wanted to find the speed of the frequency of a photon with a wavelength of 450nm

So I would use
v = c/λ
v = 299,792,458/4.5 * 10^(-11)
= 6.662054622 * 10^18

Then, if I wanted to find the energy of the photon, I would just multiply that number by planks constant (6.26 * 10^-34) and I get the energy of a quantum leap from an atom and the photon's energy itself, right?

Last edited:
You seem to have a couple of problems. First to find the units on a quantity do dimensional analysis. This means to do algebra on the units of the quantities involved. In this case we have

$$\nu = \frac c {\lambda}$$

the units of c are m/s the units of $\lambda$ are m so you have

$$\nu = \frac {\frac m s} m$$

so the units for $\nu$ are s -1 more commonly called Hertz or Hz.

Now for your numerical value, do you understand the meaning of the exponential term? Your number is off by many orders of magnitude. I get something like 7 e14 or 700,000,000,000,000Hz

450nm is 4.5*10^-7 not -11

Nano is 10^-9

Also, we usually just call Frequency "frequency" instead of "speed of frequency" since there's no real speed (in the physics sense) involved.

Integral already mentioned it, but explicitly: it's not v, it's $$\nu$$. While v normally denotes a speed, $$\nu$$ stands for a frequency, which is quite different.

Ich said:
Integral already mentioned it, but explicitly: it's not v, it's $$\nu$$. While v normally denotes a speed, $$\nu$$ stands for a frequency, which is quite different.

Even more useless info:
http://en.wikipedia.org/wiki/Nu_(letter)

To avoid confusion, I'd use "f".

zeromodz said:
Okay, I just need to grasp what the equation C = Vλ means
.
Correct me if I am wrong.
c = speed of light
v = speed of frequency
λ = wavelength

So if I wanted to find the speed of the frequency of a photon with a wavelength of 450nm

So I would use
v = c/λ
v = 299,792,458/4.5 * 10^(-11)
= 6.662054622 * 10^18

Then, if I wanted to find the energy of the photon, I would just multiply that number by planks constant (6.26 * 10^-34) and I get the energy of a quantum leap from an atom and the photon's energy itself, right?

In additon to what others mentioned...

Since you know that $E=h\nu$, you could just do this to find the energy of a photon:

$$\nu = \dfrac{c}{\lambda}$$

$$E = \dfrac{hc}{\lambda}$$

A helpful number to remember is the value of hc. So if you express your wavelength in nanometers, you can get the energy in electron volts like this:

$$E = \dfrac{1240eV\times nm}{\lambda}$$

## 1. What does the equation C=Vλ mean?

The equation C=Vλ represents the relationship between the speed of light (C), the frequency of light (V), and the wavelength of light (λ). It states that the speed of light in a vacuum is equal to the product of the frequency and wavelength of light.

## 2. How is this equation related to the energy of a photon?

The energy of a photon (E) is directly proportional to its frequency (V) and inversely proportional to its wavelength (λ). This relationship is described by the equation E=hV, where h is Planck's constant. Therefore, C=Vλ can be used to calculate the energy of a photon by rearranging the equation to E=hc/λ.

## 3. Why is the speed of light important in this equation?

The speed of light is a fundamental constant in physics and is important in this equation because it relates the two other components, frequency and wavelength, to each other. Without the speed of light, we would not be able to accurately measure or calculate the energy of a photon.

## 4. What is the significance of the frequency and wavelength in this equation?

The frequency and wavelength of light are both important properties that describe the nature of light. The frequency represents the number of waves that pass a given point in a certain amount of time, while the wavelength represents the distance between two consecutive peaks of a wave. In this equation, they are used to determine the energy of a photon.

## 5. How is this equation used in scientific research?

The equation C=Vλ and its rearranged form E=hc/λ are used in various fields of science, such as quantum mechanics and spectroscopy, to calculate the energy of photons. This information is crucial in understanding the behavior of light and its interactions with matter, which has many practical applications in technology and medicine.

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