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Refraction
Refraction
Refraction is the bending of light rays when they pass at an angle in or out of materials such as glass and water.
Law of Refraction - The Snell's Law
- The incident and refracted rays are on opposite sides of the normal at the point of incidence, and all three lie in the same plane.
- The value of (sin i)/(sin r) is constant for light passing from one given medium into another. This is known as Snell's law.
Refractive Index
The value of (sin i)/(sin r) is called the refractive index of the medium and it gives us an indication of its light-bending ability.
Answer:
Angle of incident, i = 90o - 30o = 60o
Angle of refraction, r = 45o
Refractive index,
\begin{gathered}
n = \frac{{\sin i}}
{{\sin r}} \hfill \\
n = \frac{{\sin 60^o }}
{{\sin 45^o }} = 1.22 \hfill \\
\end{gathered}
Definition of refractive index
Refractive index of a medium can be defined as the ratio of the speed of refracted light in vacuum to its speed in the medium.
Real Depth and Apparent Depth
The real depth of an object is the vertical distance of the object from the surface of the liquid.
The apparent depth of an object is the vertical distance of the image of the object from the surface of the liquid.
Refraction - From Less dense medium to Denser Medium
Light passing into an optically more dense medium is bent towards the normal
Refraction - From Denser Medium to Less dense medium
Light passing into an optically less dense medium is bent away from the normal.
Refraction - Along the Normal
When the ray is perpendicular to the refraction plane, it will not be refracted.
Phenomena Due to Refraction
- Swingming pool appears shallower than its actual depth.
- A spoon looked bent in a glass filled with water.
- Twinkling of star.
- The setting sun look oval in shape.
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