![]() The actual amount of light that is reflected depends on the composition and physical characteristics of the object. ![]() Very smooth surfaces, such as mirrors, are able to almost completely reflect the incident light, thus allowing the viewer to see his/her own reflection on them.Īngle of incidence(i) = angle of refraction(r)Ī beam of light travels at different speeds through objects of different densities. For example, light travels fastest in vacuum, slower through air, and even slower through water. This change of speed bends the light as it travels through the different mediums, causing the angle of refraction to be different to the angle of incidence.ĭifferent wavelengths of light also travel at different speeds, which causes them to bend at different angles. This is why when a full spectrum beam of light is made to travel through a prism, each of its wavelengths are separated into the colors of the rainbow. Stars too ‘twinkle’ due to the refraction of their light by the Earth’s atmosphere. While measuring the angle of refraction against the angle of incidence, as light passed through different media, he discovered that the angle of incidence of light was proportional to the angle of refraction.Īngle of incidence(i) ∝ angle of refraction(r) Refraction was first studied by the Roman scientist Ptolemy in the 2nd century CE. Later, in 984 CE, a mathematician from Baghdad, by the name of Ibn Sahl, was able to derive the full equation for refraction as given below. Where V1 and V2 represent the different velocities of light in each medium, and n1 and n2 represent the refractive index of each medium. Diffractionįor many years, scientists had debated on whether light is a linear stream of particles or a wave. Many of light’s behavior and properties led to the conclusion that it must be a stream of particles. However, the discovery of diffraction of light proved that it had wave-like qualities as well. The term ‘diffraction’ was first coined in the year 1660, by Italian physicist Francesco Grimaldi. Take a ten question quiz about this page.This occurrence advocated its wave-like behavior because if light was just a stream of particles, how could it bend around the sharp boundaries of the slit and continue moving similar to a water wave? He used it to describe the phenomenon where a single beam of light, when passed through a narrow slit, was able to split into different directions creating an interference pattern. If it has a lower amplitude, this is called destructive interference. If the resulting wave has a higher amplitude than the interfering waves, this is constructive interference. When the waves meet the resulting wave will have the amplitude of the sum of the two interfering waves.ĭepending on the phase of the waves the interference can be constructive or destructive. When one wave comes into contact with another wave this is called interference. As a result the white stripe will be less hot. A white stripe painted on the pavement will reflect more of the light and absorb less. The black pavement becomes hot from absorbing the light waves and little of the light is reflected making the pavement appear black. One example of absorption is black pavement which absorbs energy from light. This vibration absorbs or takes some of the energy away from the wave and less of the energy is reflected. In this picture the unpolarized light wave travels through the filter and then is polarized along a single plane.Ībsorption is when a wave comes into contact with a medium and causes the medium's molecules to vibrate and move. Longitudinal waves, such as sound, cannot be polarized because they always travel in the same direction of the wave. Light waves are often polarized using a polarizing filter. Polarization is when a wave oscillates in one particular direction.
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