What are the difference between total internal reflection and reflection of light by a mirror
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By "simple reflection," do you mean a mirror? That's a different animal altogether. You have light in a transparent material interacting with the boundary of a non-transparent material. In general, when light strikes such a surface, some of the light scatter, some will be absorbed by the material as heat, and the rest will reflect. A mirror reflects almost all of it. A perfect mirror would reflect all of it, but that is not Total Internal Reflection (TIR).
TIR occurs when both materials are transparent. So the light can, in theory, pass through the boundary into the second material. This is called “transmission.” But not all of the light transmits; some will still reflect. That's why you can see a dim reflection in a window. If this is what you mean by "simple reflection," then TIR is a special case of the physics that defines how much of the light experiences either process.
If light in air hits a glass surface straight on - that is, along the line that is perpendicular to the surface, called the surface normal - the light that enters the glass continues along the same path. If it is not straight on, then a fraction of the light transmits, and will bend toward the surface normal as it does. Because it bends inwards, the range of angles in the glass is less than the range in the air. The maximum angle it can have in the glass is called the Critical Angle, or C. It is about 40° for glass.
This process is exactly reversed when light already inside a glass object hits a surface. If it strikes the surface at an angle that is less than C, the transmitted light bends away from the surface normal and ends up between 0° and 90°. If it strikes at more than C (see note 1), there is no angle it can have in the air that satisfies the laws of physics. So all of it reflects. This is called Total Internal Reflection (see note 2).
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Note 1: This can’t happen in a window. Because the two surfaces are parallel, the light strikes the back of the pane at the same angle it had upon entering, which by definition is less than C. Some binoculars use prisms designed so that the angle will always be more than C, so the prism acts like a perfect mirror.
Note 2: "Internal" means "stays inside the first material," not "stays inside an object." Since "reflection" means the same thing, the word "internal" is redundant. One of the most common examples of TIR is that air bubbles in water appear shiny. Most of the light hitting the bubble can't enter it due to TIR, and so reflects “externally.”
So “Total Internal Reflection” could be called a misnomer. The incorrect naming leads to a common myth about rainbows. While they are indeed caused by “internal reflections,” it is not TIR. TIR is impossible in the raindrops for reasons similar to why it is impossible in windows.
TIR occurs when both materials are transparent. So the light can, in theory, pass through the boundary into the second material. This is called “transmission.” But not all of the light transmits; some will still reflect. That's why you can see a dim reflection in a window. If this is what you mean by "simple reflection," then TIR is a special case of the physics that defines how much of the light experiences either process.
If light in air hits a glass surface straight on - that is, along the line that is perpendicular to the surface, called the surface normal - the light that enters the glass continues along the same path. If it is not straight on, then a fraction of the light transmits, and will bend toward the surface normal as it does. Because it bends inwards, the range of angles in the glass is less than the range in the air. The maximum angle it can have in the glass is called the Critical Angle, or C. It is about 40° for glass.
This process is exactly reversed when light already inside a glass object hits a surface. If it strikes the surface at an angle that is less than C, the transmitted light bends away from the surface normal and ends up between 0° and 90°. If it strikes at more than C (see note 1), there is no angle it can have in the air that satisfies the laws of physics. So all of it reflects. This is called Total Internal Reflection (see note 2).
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Note 1: This can’t happen in a window. Because the two surfaces are parallel, the light strikes the back of the pane at the same angle it had upon entering, which by definition is less than C. Some binoculars use prisms designed so that the angle will always be more than C, so the prism acts like a perfect mirror.
Note 2: "Internal" means "stays inside the first material," not "stays inside an object." Since "reflection" means the same thing, the word "internal" is redundant. One of the most common examples of TIR is that air bubbles in water appear shiny. Most of the light hitting the bubble can't enter it due to TIR, and so reflects “externally.”
So “Total Internal Reflection” could be called a misnomer. The incorrect naming leads to a common myth about rainbows. While they are indeed caused by “internal reflections,” it is not TIR. TIR is impossible in the raindrops for reasons similar to why it is impossible in windows.
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Total internal reflection: the light through one medium and refracts and then that refracted ray acts as light and pass through other medium and emerge out
This happen in diamond
Reflection of light on mirror: the light ray which passed on to a mirror will reflect back with same angle in opposite direction. Therefore angle of incidence =angle of reflection
This happen in diamond
Reflection of light on mirror: the light ray which passed on to a mirror will reflect back with same angle in opposite direction. Therefore angle of incidence =angle of reflection
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