F486-Dispersi cahaya ,teori plus contoh soal

Summary

In this video, the concept of light dispersion is explained, focusing on how white light separates into a spectrum of colors, like a rainbow, when passed through a prism. The cause of this dispersion is the varying refractive indices for different colors of light. The script covers the process of how light bends at different angles, leading to color separation. It also explains related concepts like deviation angles and how to calculate dispersion, including step-by-step solutions for example problems. Key formulas and the impact of the prism's apex angle are highlighted in the discussion.

Takeaways

• 😀 Dispersion of light refers to the phenomenon where white light splits into its constituent colors, creating a rainbow-like spectrum.
• 😀 The cause of light dispersion is due to different refractive indices for different wavelengths of light, resulting in varying angles of refraction.
• 😀 To observe light dispersion, direct white or polychromatic light onto a prism, ensuring the light does not strike the surface perpendicularly.
• 😀 Light is separated into different colors such as red, orange, yellow, green, blue, indigo, and violet (ROYGBIV) as a result of this dispersion.
• 😀 The wavelength of red light is the longest (around 700 nm), while violet light has the shortest wavelength (around 400 nm).
• 😀 Dispersion can be quantitatively measured by calculating the angular deviation between the paths of red and violet light after passing through the prism.
• 😀 The symbol 'V' represents dispersion, calculated as the difference in deviations between the violet and red light paths.
• 😀 If the prism's apex angle is less than 15°, the dispersion can be approximated using a simplified formula involving the refractive indices and the prism's apex angle.
• 😀 Snell's Law governs the refraction of light through the prism and is used to calculate the angles of deviation for both red and violet light.
• 😀 An example problem shows how to calculate dispersion by applying Snell’s Law and using given indices of refraction for red (1.64) and violet (1.67) light.

Q & A

What is light dispersion?

Light dispersion is the phenomenon where white light splits into its component colors, forming a rainbow. This happens because the refractive index of a material varies for different colors of light, causing each to bend at a different angle.

How does light dispersion occur in a prism?

When white or polychromatic light strikes one side of a prism at an angle that is not perpendicular, it refracts inside the prism. Due to the differing refractive indices for each color, the light bends at different angles, leading to the separation of colors into a spectrum.

Why does red light bend less than violet light in a prism?

The refractive index for red light is lower than that for violet light. This means that red light bends less than violet light when passing through the prism, causing the colors to spread out.

What is the relationship between wavelength and color in the light spectrum?

In the visible light spectrum, red light has the longest wavelength (around 700 nm), while violet light has the shortest wavelength (around 400 nm). As the wavelength decreases, the frequency increases.

What is the formula for calculating dispersion in light passing through a prism?

Dispersion (V) is the difference in deviation angles between red and violet light. Mathematically, it's calculated as the deviation of violet light minus the deviation of red light.

What does the term 'angle of deviation' refer to?

The angle of deviation refers to the angle between the direction of the incident light and the refracted light. It represents how much the light has deviated due to refraction.

How can you calculate the deviation angle for red and violet light?

To calculate the deviation angle for both red and violet light, you apply Snell's Law of refraction. For each color, you determine the angles of incidence and refraction at each surface of the prism, and then calculate the deviation.

What is the formula for finding the minimum deviation of light in a prism?

The minimum deviation occurs when the light experiences the smallest bending in the prism. The formula for minimum deviation (δ_min) is given by: δ_min = I1 + R2 - β, where I1 is the angle of incidence, R2 is the angle of refraction, and β is the apex angle of the prism.

How does the apex angle of the prism affect the dispersion of light?

The apex angle (the angle at the top of the prism) determines the amount of deviation light experiences as it passes through the prism. A smaller apex angle results in less dispersion, while a larger apex angle increases the dispersion.

What is the significance of using Snell's Law in calculating light deviation in a prism?

Snell's Law is crucial for determining how light bends when transitioning between different media. It provides the mathematical relationship between the angles of incidence and refraction, allowing for precise calculations of the deviation angles for both red and violet light.