Could you please explain "total internal reflection" in simple terms (suitable for a 12/13 yr old.
Total internal reflection (TIR) occurs when light enounters a surface between two materials at an angle of incidence greater than a certain critical angle. When TIR occurs, all of the light is reflected and none of it can cross the surface into the other material.
TIR only happens when the light tries to enter a material in which the speed of light is HIGHER. It happens, for example, inside glass fiber optics. All of the light stays inside the glass until it comes out the other end.
This is hard to explain without a diagram.
Imagine that we have a boundary between two materials. This could be say the edge between glass and air, or between plastic and water, or between two solids say perspex and glass. Each of these pairs have a differencet refractive index, i.e. bends light through different angles.
When light crosses the boundary between the two materials with different refractive indices, the light beam will be refracted at the boundary between the two. However, if the angle of approach (incidence) is close to being parallel to the boundary then the light is refracted so that it travels along the boundary and the light will stop crossing the boundary altogether. The angle where this happens is called the critical angle. If the angle is greater than the critical angle the light is reflected back and this is total internal reflection.
It is worth remembering that this
only occurs where light travels from a medium with a higher refractive index to one with a lower refractive index. For example, it will occur when passing from glass to air, but not when passing from air to glass.
There is a good diagram at
(Broken Link Removed)
also
http://www.fiberoptics4sale.com/Merchant2/fofs_img/total-internal-reflection.gif
Any help?
Of course! I'd be happy to explain total internal reflection in simple terms.
Total internal reflection occurs when light traveling through a transparent material, such as water or glass, reaches a boundary with another material, like air or a different type of glass, at a certain angle. When this happens, instead of bending or refracting, the light gets fully reflected back into the material it came from.
Let me explain how this works using an example: Imagine you're swimming in a pool and you're looking at the water from an underwater window. When you look straight ahead, you can see everything above the water's surface clearly. However, if you tilt your head slightly, you may notice that the view becomes distorted or even completely blocked. That's because the light rays are hitting the water-air boundary at an angle where total internal reflection occurs.
To understand why this happens, you need to know about the concept of the critical angle. The critical angle is the specific angle of incidence at which total internal reflection takes place. If a light ray hits the boundary at an angle greater than the critical angle, it will be reflected back inside the material.
For example, if you shine a laser pointer through a glass of water, the light will bend and move out of the water into the air. But if you point the laser at a very steep angle, the light won't bend and instead will reflect back into the water. This is total internal reflection in action.
Total internal reflection has many practical applications. For instance, it is used in optical fibers to transmit information over long distances without losing much signal strength. It is also utilized in prisms and camera lenses to focus and manipulate light.
I hope that helps! Let me know if you have any more questions.