How do I calculate the angle of incidence?

What is the relation between angle of incidence, angle of refraction, angle of emergence and angle of deviation?

• I want to know the relationship between angle of incidence, refraction, emergence and deviation. I mainly want to know about the deviation one. Please explain the whole thing in ...show more

• Answer:

  In the diagram at left, a light ray PO strikes a vertical mirror at point O, and the reflected ray is OQ. By projecting an imaginary line through point O perpendicular to the mirror, known as the normal, we can measure the angle of incidence, θi and the angle of reflection, θr. The law of reflection states that θi = θr, or in other words, the angle of incidence equals the angle of reflection. The angle between θi and θr is 90 degrees. Refraction is the change in direction of a wave due to a change in its transmission medium. Refraction is essentially a surface phenomenon. The phenomenon is mainly in governance to the law of conservation of energy and momentum. Due to change of medium, the phase velocity of the wave is changed but its frequency remains constant. This is most commonly observed when a wave passes from one medium to another at any angle other than 90° or 0°. Refraction of light is the most commonly observed phenomenon, but any type of wave can refract when it interacts with a medium, for example when sound waves pass from one medium into another or when water waves move into water of a different depth. Refraction is described by Snell's law, which states that for a given pair of media and a wave with a single frequency, the ratio of the sines of the angle of incidence θ1 and angle of refraction θ2 is equivalent to the ratio of phase velocities (v1 / v2) in the two media, or equivalently, to the opposite ratio of the indices of refraction (n2 / n1): \frac{\sin\theta_1}{\sin\theta_2} = \frac{v_1}{v_2} = \frac{n_2}{n_1} . In general, the incident wave is partially refracted and partially reflected; the details of this behavior are described by the Fresnel equations. https://s.yimg.com/hd/answers/i/c0aa196b482745d9b8202137d6067f49_A.png?a=answers&mr=0&x=1398240592&s=90a4ed58c55dd197d64df7869bfc5b8b