How Light Behaves. Optics Study of light . Illumination. Luminous – when a body gives of light Incandescent – when a body that gives of light through when heated A body is illuminated when you can see it because it reflects light towards your eyes.
Study of light
A body is illuminated when you can see it because it reflects light towards your eyes.
Radiant flux – the amount of energy radiated in a unit of time by an electromagnetic wave source. Part of this radiation that enables us to see is called the luminous flux, F. Measured in lumen (lm).
A – Area of sphere
R – Radius of the sphere
Some light may be absorbed by molecules on the surface or within the
Imagine a line perpendicular to te reflecting surface. Such line is called normal . The angle between the path of an incoming ray and the normal is called the angle of incidence. The reflected ray makes the same angle to the normal as the incoming ray, but the other side of the normal. Reflection works this way even when it involves rough surfaces. Whenever a ray reflects from a surface, it has an equal angle to the normal at that spot it had before the reflection.
When a light reflects from a smooth surface, all of its rays reflect in the same directions. When light reflects from a rough surface, the rays reflect in many directions because the normals at all spots on the surface points many ways.
We have a relation
sin i/sin r = v1/v2
To observe refraction, place a pencil in a glass of water and then look at the pencil from the top and one side. The pencil appears bent at the water surface. The light from the top part of the pencil comes directly to you eyes. The rays from the bottom part pass through the surface between the water and air. There the rays refract, and so they seem to have come from a pencil bottom bent from the pencil top.
n = c/v
n1 sin i=n2 sin r
The wavelength of the light can be calculated from the distance between the center and the first bright band of the screen.
Hologams, are specialized interference patterns recorded on a thin film emulsion on glass or plastic, enabling you eyes to see exactly the pattern of light waves that was reflected by a three-dimensional object.