Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Prev NEXT. Physical Science. Cite This! Print Citation. The law of refraction or Snell's law states that the ratio of the sine of angles of incidence and refraction is equal to the ratio of the refractive index of the first and the second media respectively.
The index of refraction of medium 1 and 2 are n 1 and n 2 , respectively. A light ray from a lighter medium when entered into a denser medium bends towards the normal of the surface.
On the other hand, a ray emerging from a denser medium entering into a lighter medium bends away from the normal. When the incident ray is equal to the normal of the surface, the direction of the light stays unaltered as it enters into the second medium.
The ratio of the speed of light in a vacuum to its speed in that particular medium is known as the refractive index or index of refraction. For example, the refractive index for a vacuum is always 1. The refractive index of air standard conditions is 1. Fig: b. A convex lens produces a convergent beam of light, when a parallel beam falls on it Fig: c.
A beam of light may be parallel, convergent or divergent. A ray only conveys the direction of light. It refers to an optical wave that has a finite width. It can come directly from the source through empty space, such as from the Sun to Earth. Or light can travel through various media, such as air and glass, to the person.
Light can also arrive after being reflected, such as by a mirror. In all of these cases, light is modeled as traveling in straight lines called rays.
Light may change direction when it encounters objects such as a mirror or in passing from one material to another such as in passing from air to glass , but it then continues in a straight line or as a ray. The word ray comes from mathematics and here means a straight line that originates at some point. It is acceptable to visualize light rays as laser rays or even science fiction depictions of ray guns. Figure 1. Three methods for light to travel from a source to another location.
It can travel through media like air and glass.
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