Gcse Coursework Science Examples Of Transparent

Refractive index

The amount of refraction depends on:

  • the angle the light hits the boundary between the substances

  • the difference in relative densities [density: A measure of the quantity of some physical property (usually mass) per unit length, area, or volume (usually volume).] , between the two media (which determines how much the speed of light changes)

The degree to which a material slows the speed of light (compared to its speed in a vacuum) is its refractive index [refractive index: A measurement of the speed at which light passes through a substance, relative to the speed of light in a vacuum. It also indicates how much light will be bent when it passes from one substance into another.] . This can be calculated using the equation:

refractive index = sin i/sin r

Where:

i is the angle of incidence

r is the angle of refraction

Worked example

A beam of light hits a glass block. The angle of incidence [angle of incidence: Angle between the normal and a light ray travelling towards a mirror or into another substance.]  angle of incidence is 55°. The angle of refraction [angle of refraction: Angle between the normal and a refracted light ray.]  inside the block is 33°. Calculate the refractive index.

A ray of light passing from the air into glass, showing the incident ray (in the air) and the refracted ray (in the glass).

Step 1: Work out the sine of angle i

sin 55 = 0.819

Step 2: Work out the sine of angle r

sin 33 = 0.545

Step 3: Divide sin i by sin r

refractive index = sin i ÷ sin r

refractive index = 0.819 ÷ 0.545 = 1.50

A refractive index of 1.5 will slow down light and bend it toward the normal inside the glass block.

Поразительно, - пробурчал он, - что сотрудникам лаборатории систем безопасности ничего об этом не известно. ГЛАВА 47 - Шифр ценой в миллиард долларов? - усмехнулась Мидж, столкнувшись с Бринкерхоффом в коридоре.  - Ничего. - Клянусь, - сказал .

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