MATERI FISIKA SMA KELAS 12 | GEJALA KUANTUM | RADIASI BENDA HITAM DAN PERGESERAN WIEN

Summary

In this video, Ivan introduces the concept of black body radiation and the Wien displacement law. He explains black body radiation, highlighting how electromagnetic waves are absorbed and emitted by a black body when heated. The intensity of radiation depends on temperature and wavelength. Ivan discusses the mathematical relationships behind these phenomena, including Stefan-Boltzmann's law and the formula for radiation intensity. Additionally, he covers the Wien displacement law, which shows how the peak wavelength shifts to shorter wavelengths as temperature increases. The video offers an insightful overview of quantum phenomena related to radiation and temperature.

Takeaways

• 😀 Black body radiation refers to the radiation emitted by a perfect black body that absorbs all incoming electromagnetic waves.
• 😀 A black body is a closed container with a small hole through which electromagnetic waves can enter, but very few can escape.
• 😀 When the electromagnetic waves inside the black body container strike the walls, their energy decreases due to multiple collisions.
• 😀 A black body does not transmit electromagnetic waves, instead it absorbs and emits radiation when heated.
• 😀 The intensity of radiation emitted by a black body is directly related to its temperature and wavelength.
• 😀 As the temperature of the black body increases, the peak intensity of the emitted radiation also increases.
• 😀 The mathematical relationship for radiation intensity can be represented by the Stefan-Boltzmann law, where radiation is proportional to the fourth power of temperature.
• 😀 The formula for radiation intensity is: I = e * σ * T^4, where e is emissivity, σ is the Stefan-Boltzmann constant, and T is the absolute temperature.
• 😀 Wien's Displacement Law states that the peak wavelength of emitted radiation shifts to shorter wavelengths as temperature increases.
• 😀 The mathematical expression for Wien's Law is: λ_max * T = C, where λ_max is the peak wavelength, T is temperature, and C is the Wien's constant (2.89 × 10^-3 m·K).

Q & A

What is the main topic discussed in the video?

The main topic discussed is quantum phenomena, specifically black body radiation and the Wien displacement law.

What is a black body in the context of this video?

A black body is an object that absorbs all electromagnetic radiation that enters it, without transmitting any. It can also emit radiation when heated.

What happens when electromagnetic waves enter a black body?

When electromagnetic waves enter a black body, they are unlikely to escape. If they hit a wall inside, their energy decreases with each collision.

What happens when a black body is heated?

When a black body is heated, it emits radiation whose intensity is a function of its temperature and wavelength.

How does temperature affect the intensity of radiation emitted by a black body?

As the temperature increases, the peak intensity of radiation from a black body increases. This relationship is shown in a graph where the intensity rises as temperature increases.

What is the formula related to the intensity of radiation from a black body?

The intensity of radiation is described by the Stefan-Boltzmann law, expressed as p = e * σ * A * T⁴, where e is the emissivity, σ is the Stefan-Boltzmann constant, A is the surface area, and T is the temperature in Kelvin.

What is the Stefan-Boltzmann constant and its value?

The Stefan-Boltzmann constant is 5.67 × 10⁻⁸ W/m²K⁴, and it relates the intensity of radiation emitted by a black body to its temperature.

What does the Wien displacement law describe?

The Wien displacement law describes how the peak wavelength of radiation emitted by a black body shifts to shorter wavelengths as the temperature increases.

What is the mathematical formula for the Wien displacement law?

The formula for the Wien displacement law is λ_max * T = C, where λ_max is the peak wavelength, T is the temperature in Kelvin, and C is the Wien constant, approximately 2.89 × 10⁻³ m·K.

How does the peak wavelength change with increasing temperature according to the Wien displacement law?

As the temperature increases, the peak wavelength shifts to shorter wavelengths. This means the radiation becomes more intense at shorter wavelengths as the temperature rises.