# What is the magnitude of the Electric field inside a light wave?

• silverdiesel
In summary, the magnitude of light varies greatly, but for a basic understanding, the light from a computer screen is likely on the order of 10^-6 N/C. The intensity of light can be derived from the Intensity equation, with a value of 1300 W/m^2 being equivalent to 1000 N/C. However, this value may differ for different sources of light, such as the sun, and may only encompass certain parts of the electromagnetic spectrum. The amplitude of the electric field is directly related to the intensity of light, with higher intensity beams having a larger amplitude. For example, a laser beam can have a very strong electric field, while the light from a star has a weaker electric field. This difference in amplitude
silverdiesel
I know the magnitude varys a lot, but I am just looking for some basic intuitive idea of light. Is the magnitude of light from my computer screen on the order of 10^6 N/C or more like 10^-6 N/C?

Nevermind, I finally found it in my gen phys 2 book derived from the Intensity. 1300 W/m^2 ~ 1000 N/C

I think the figure you quoted is the value for the intensity of light from the sun at a distance of 1 AU. But I'm not sure if that includes the entire EM spectrum, or just heat and visible light.

Classically at least, the field can vary widely, a laser beam for example might have a huge E field (enough to induce air to ionise in some cases). The light from a star obviously has a much weaker E field. Note that the amplitude of the E field is related to the intensity of a light beam. To give you an idea in terms of numbers (in intensity), we can detect 10^-14 W/m^2 and produce 10^12 W/m^2 (as a conservative estimate), that's 26 orders of magnitude right there.

Claude.

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## 1. What is the difference between electric field magnitude and intensity inside a light wave?

The electric field magnitude refers to the strength of the electric field at a specific point inside the light wave, while intensity refers to the amount of energy carried by the light wave per unit area per unit time. In other words, electric field magnitude is a measure of the strength of the electric field, while intensity is a measure of the brightness of the light wave.

## 2. How is the magnitude of the electric field inside a light wave related to its frequency?

The magnitude of the electric field inside a light wave is directly proportional to the frequency of the light wave. This means that as the frequency increases, the electric field magnitude also increases, and vice versa. This relationship is described by the equation E=hf, where E is the electric field magnitude, h is Planck's constant, and f is the frequency of the light wave.

## 3. Does the magnitude of the electric field inside a light wave vary with the medium it travels through?

Yes, the magnitude of the electric field inside a light wave can vary depending on the medium it travels through. This is because the medium can affect the speed and direction of the light wave, which in turn can affect the magnitude of the electric field. For example, the electric field magnitude inside a light wave will be lower in a denser medium compared to a less dense medium.

## 4. Can the magnitude of the electric field inside a light wave be negative?

Yes, the magnitude of the electric field inside a light wave can be negative. This is because electric fields can have both positive and negative values, depending on the direction of the field. In a light wave, the electric field is constantly changing direction, so it is possible for the magnitude to be negative at certain points in time.

## 5. How is the magnitude of the electric field inside a light wave related to the amplitude of the wave?

The magnitude of the electric field inside a light wave is directly proportional to the amplitude of the wave. This means that as the amplitude increases, the electric field magnitude also increases, and vice versa. Amplitude is a measure of the maximum displacement of the electric field from its equilibrium position, so a larger amplitude results in a stronger electric field magnitude.

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