Refração da luz: Lei de Snell. 2/4

Summary

This video lesson explains the concept of light refraction, focusing on Snell's Law and the behavior of light as it passes through different media. It demonstrates how light changes speed and direction when moving between mediums with different refractive indices. The script emphasizes two key rules: when light moves from a medium with a lower refractive index to one with a higher index, it bends towards the normal; conversely, when it moves from a higher to a lower refractive index, it bends away. Additionally, the video clarifies that when light strikes the normal directly, no deviation occurs despite the change in medium.

Takeaways

• 😀 Snell's Law governs the refraction of light when it passes from one medium to another.
• 😀 Refraction involves a change in the speed of light as it enters a different medium, potentially altering its direction.
• 😀 Snell's Law is expressed as: sin(θ1)/sin(θ2) = n2/n1, where θ1 and θ2 are angles of incidence and refraction, and n1 and n2 are refractive indices.
• 😀 When light enters a medium with a higher refractive index, it bends towards the normal (the perpendicular line to the interface).
• 😀 When light enters a medium with a lower refractive index, it bends away from the normal.
• 😀 The refractive index determines how much light will bend at the interface between two media.
• 😀 A light ray that enters exactly along the normal line will not deviate, even though its speed changes.
• 😀 The relationship between the angles of incidence and refraction helps us predict how light will behave in different media.
• 😀 Light will always bend towards the normal when transitioning from a less dense medium to a denser one.
• 😀 When light passes from a denser medium to a less dense one, the angle of refraction increases, moving away from the normal.
• 😀 The key takeaway is that Snell’s Law helps to predict how light bends based on the refractive indices of the media involved.

Q & A

What is Snell's Law?

Snell's Law describes the relationship between the angles of incidence and refraction when light passes through the boundary between two media with different refractive indices. It is given by the equation: (n1 * sin(θ1)) = (n2 * sin(θ2)), where n1 and n2 are the refractive indices of the two media, and θ1 and θ2 are the angles of incidence and refraction, respectively.

What happens to light when it passes from one medium to another with a different refractive index?

When light passes from one medium to another with a different refractive index, its speed changes. This change in speed can cause the light to bend, which is known as refraction. The direction in which the light bends depends on the relative refractive indices of the two media.

What does it mean for light to 'bend towards the normal'?

When light bends towards the normal, it means that it is moving from a medium with a lower refractive index to a medium with a higher refractive index. The light ray slows down and the angle of refraction decreases, causing the ray to move closer to the normal line (the perpendicular line to the surface separating the two media).

What happens when light moves from a higher refractive index to a lower one?

When light moves from a medium with a higher refractive index to a medium with a lower refractive index, the light bends away from the normal. This is because the light speeds up as it enters the second medium, resulting in an increase in the angle of refraction.

Why does the angle of refraction decrease when light passes from a lower refractive index to a higher one?

The angle of refraction decreases when light passes from a lower refractive index to a higher one because the speed of light decreases in the denser medium. According to Snell's Law, a decrease in speed leads to a smaller angle of refraction, causing the light to bend towards the normal line.

Can light change its path if it enters exactly along the normal?

No, light does not change its path if it enters exactly along the normal. In this case, the angle of incidence is 0°, and according to Snell's Law, there is no deviation in the light's path, even though the light is changing media. The light simply continues straight without bending.

What is the significance of the refractive index in the refraction of light?

The refractive index of a medium determines how much light will bend when it enters that medium. A higher refractive index means that light will slow down more, causing a greater bend towards the normal. Conversely, a lower refractive index causes light to speed up and bend away from the normal.

What happens when light passes from a medium with refractive index √2 to one with refractive index 1?

When light passes from a medium with a refractive index of √2 to one with a refractive index of 1, the light bends towards the normal. The example given shows that with a 45° angle of incidence, the refracted angle is 30°, demonstrating that the light slows down and bends towards the normal.

What rule can be derived from observing how light bends when moving between media with different refractive indices?

The rule is: when light moves from a medium with a lower refractive index to one with a higher refractive index, it bends towards the normal. When it moves from a higher refractive index to a lower one, it bends away from the normal.

How does the refracted angle change when light passes from a medium with refractive index √3 to √2?

When light passes from a medium with refractive index √3 to a medium with refractive index √2, the light bends away from the normal. The refracted angle increases from 45° (the angle of incidence) to 60°, indicating that the light is speeding up and moving further from the normal.