Chaoter 3 - Optics Flashcards
What is the reflection of light?
The reflection of light is a phenomenon of light bouncing back after falling on an object.
Here’s how its described:
the ray coming towards the surface is an incidant ray.
Ray that bounces is a reflected ray.
Point of incidence is where the light hits.
Normal is the line drawn at a right angle to the incidence point.
Incidence angle’s between the nornal and the point of ince.
Reflection angle is between the normal and reflec points.
What are the laws of reflection?
The incident ray and the normal all lie on the sane plane.
The angle of reflection equals the angle of incidence. 0i = 0r
What are the terms used for spherical mirrors?
Center of curvature: the cebter of sphere from which the mirror is formed.
Radius of Curvature is the radius of the sohere of which the mirror is a section of.
Pole P: is the midpoint of the spherical mirror.
Principle Axis is a straight line drawn through the center of curvature and the pole.
What is a focal point?
A beam of light is directed towards either a convex or a concave mirror along its principle axis. After redirecting, the rays converge as if they originate from a single point, this is called the focal point F.
Focal length of the spehrical mirror is the distance from the pile of the mirror to the focus point of the object. It is measured in metres.
What is the spherical mirror equation?
It is a precise mathematical relationship between the object distance and the image distance for a given mirror.
It includes fpcal length f, height of the object h’o, height of the image h’m, distance of the object from the mirror d’o, distance of the image from the mirror d’i, and magnification M.
Give an example of the spherical mirror equation?
Consider a ray meeting the mirror at its midpoint, where the principle axis is the normal of the mirror. As a result, the ray reflects back at an angle of refelction 0 below the principle axis that is equal to its incident angle 0 above the principle axis. This means that the ratios of its travel path formed triangles are equal, which follows the ratios of equivalent triangles.
Ho/-hi = do/di. Hi is negative because the image is inverted.
What is refraction?
Change in the direction of light as it passes from one medium to another of different densities. It is the changing of speed when wave travels through mediums. Angles change directions.
Terms used:
Incident ray: light before reaction.
Refracted ray
Point of incidence: where light strikes a surface.
Normal, incidence angle and refractiom angle.
What is the refractive index?
The ratio of the speed of light in a vacuum to the speed of light in a specific medium is constant and is called an index refraction. If c is the speed of light, and v is the speed of light in a medium, then mathematically
N = c / v
The index of refraction is a unit less quantity having a value for an optical medium that is always greater than 1. So by definition, the index of refraction of a vacuum is 1.
What is snell’s law?
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What is snell’s law?
Snell’s Law describes how light bends, or refracts, when it passes from one material into another with a different density (like from air into water). It states that the angle at which the light enters the new material is related to the angle at which it exits, and the ratio of the sine of these angles is constant for the two materials.
What is total internal refraction?
When light strikes a transparent boundary, some is reflected. If this light originates in an optically denser medium like from glass to air, the amount of reflection can be greater than the amount of refraction.
With an increase in the angle of incidence, the angle of refraction increases, eventually reaching 90 degrees. At this stage, light rests at the boundry of two mediums, this angle is known as a critical angle.
Beyond this angle, there is no refraction and light reflects back into the denser medium. This is known as total internal refraction.
What are the conditions for total internal refraction?
Light must travel from a dense material into a less dense medium.
Angle of incidense must exceed angle 0c (critical angle) associated with the medium.
What is the equation for a critical angle?
Substitute 01 with 0c and 02 with 9p degrees.
N1 sine0c = n2sin90
Since sin90 euals 1, therefore n1sin0c=n2 or sine0c= n2/n1
What are optical fibres?
Cables with cylindrical shapes that consist of three concentric sections: the core, the cladding, and the jacket. They are used transmit info bu light pulses using internal reflection.
The innermost layer contains thin strangs made of plastic or glass called core. The material surrounding it has different properties and is the cladding, the boundry between which acts as a reflector that prevents light from escaping. All light hits this boundry at an angle beyon critical no light escapes.
The material encassing the entire fibre system is the jacket, and it prevengs it from moisture and other damage.
What is a prism?
Prismd are made of transparent materials like glass to scatter white light into constitent colors called a spectrum. They are made eith orecise cuts and angles on a rectangular base with triangular sides.
