A prism is an optical object and that has the ability to refract light. It has flat and polished surfaces with an angle (depending on their use) between them. Examples of real life prisms are glass, plastic and fluorite (Adorno 3).
There are several types of prisms. These include dispersive prisms, reflective prisms, beam-splitting prisms, polarizing prisms and deflective prisms. Dispersive prisms split light waves into its constituent components while reflective prisms change the direction. This is done by rotating, inverting or displacing the beam.
Beam-splitting prisms split light into several rays while polarizing prisms split light into rays with varying polarizations. Deflective prisms deflect light rays by certain angles.
Refraction is a change of state of a wave by passing the wave through a different medium for that change to effect. Examples of waves in real life that can be refracted are light. This is why an average 30cm ruler placed in a glass with clear appears bent.
There are several types of prisms. Of importance to this paper is the dispersive prism whose properties include breaking light into several components i.e. the spectral colors as in a rainbow.
This paper seeks to explain how a ray of light can be broken into the several components and if the reverse i.e. joining these components into a single ray of light is possible. We shall also address in detail whether this refractive property can have any application on our day to day lives.
The bending of a wave when it is passed through a medium where its speed is different defines the refractive ability of light. Light is passed through a slower medium from a fast medium. Bending occurs at the precipice between the two media and it magnitude depends on the indices of refraction of the two media in what is defined in Snell’s Law (Blackstock 187).
Willebrord Snell is a Dutch Physicist who defined the refractive ability in a law that defines the relationship between the angles of incidence and refraction for a wave impinging on an interface between two media with indices of refraction.
The mathematical derivation is thus:
Ni * Sin (Ai) = Nr * Sin (Ar)
Ni/ Sin (Ar) = Nr/ Sin (Ai)
Ni —> Refractive index of the first media (where light is exiting)
Ai —> Angle of incidence between light ray and the normal to the medium of the interface
Nr —> Refractive index of the second media (where light is entering)
Ar —> Refractive angle between the light ray and the normal to the medium interface
The refractive indices of most material are available on the public domain. This index varies with the wavelength or color of the light used in a criteria called dispersion. Hence lights of various colors refract differently and to exit the media at different angles thus creating an effect similar to a rainbow.
The best objects to use to refract light and that will form a more relevant relation with our topic of study are prisms. Prisms can disperse light over much larger frequency bandwidth hence are applied for most applications of broad-spectrum spectroscopy. They again don’t have challenges arising from overlapping spectral orders.
The reverse of refraction is also true. Light that has been split in its spectoral components can be rejoined to reform the original light wavelength. The spectoral components are passed through the same media such as prism and due to the difference in refractive index of the media, the light particles are rejoined(Smith 87).
However, if it were the case of a prism, the second prism should be place in reversed manner so as to able to achieve the joining of the light particles.
This is the same principle that has been applied in the creation of laser beams.
So then what are the applications of refraction of light in real life situations aside from what might happen in the Physics lab? Refraction has been applied in various areas of man’s life. This includes the following areas;
- Used by scientists to analyse the composition of bodies in outer space. A beam of beam directed at space is able to refract and show it components and that of bodies around it. The size and composition of the bodies is then determined.
- Refraction of light is central to the functionality of optic fibre cables used for data communication in Telecoms and on networks. Optic fibre cables are made of differentiated layers of glass. Each layer of glass has its own refractive index hence making it possible to send down a wave of light for a significant length. The refractive slopes difference of the layers ensures a desired wavelength travels forward instead of being absorbed or redirected in a way that interrupts the signal.
- People with poor eyesight have also greatly benefited from the application of the principle of refraction in lenses on spectacles. When the lens of the natural eye develops a shape that interferes with images, corrective glasses with refractive index usually restores normal vision.
Adorno, Theodor W. “Prisms.” Prisms (1967): 3.
Blackstock, David T. Fundamentals of Physical Acoustics. CANADA: JOHN WILEY & SONS, 2000.
Smith, A. Mark. “Descartes’s Theory of Light and Refraction: A Discourse on Method.” Descartes’s Theory of Light and Refraction: A Discourse on Method (1987): 87.