Light.ppt

LIGHT

CREATED BY :IZZATUN NUR ALIFAH

09330191

LIGHT

• Light is an electromagnetic wave, namely the wave the vibration of which is electric field and magnetic field.

• Light is included into transversal wave.• Light can spread without medium, so light can

spread in vacuum.

While several properties of light among other are :

• Spreading according to straight line• Has energy• Can be seen• Radiated in the form of radiation• Has spreading direction perpendicular to

vibration direction• Can experience reflection, refraction,

interference, diffraction, and polarization

Bodies that can spread light is called light source. While bodies

that cannot spread light theirself is called dark body.

Sorting light sources

Natural vs. Man-made (artificial)

Are these light sources?

moonwater

mirror

These items are not light sources, instead they are reflecting light from other sources.

lightsource

Light rays travel in straight lines from the light source.

When it hits an opaque object, some light is absorbed and the rest reflects off.

If the object is transparent, light rays pass through it easily.

If the object is translucent, some light can pass through, but the rest of the light will be reflected.

Light Reflection

Angle of incidence

Angle of reflection

The ‘angle of

reflection’ is always

equal to the ‘angel of

incidence’.r = i

on

off

If a light hits a body surface

commonly will be reflected.

Law of Reflection

• Incident angle, normal line and reflected ray lie on one flat plane

• Incidence angle is equal to reflected angle (i=r)

How does light form shadows?

Light rays travel in straight lines, radiating out from the light source.

If rays are blocked by an opaque object a shadow forms where the light cannot reach.

If the light source is moved closer to the object, more light is blocked and a larger shadow is formed.

lightsource

lightsource

Specular Reflection

Reflection rayIncidence ray

happens if the stream of light falls on the body that its surface is smooth and shiny, so direction of the light reflection goes to certain direction.

The diffuse reflection

Incidence ray

Reflection ray

Happens if the stream of light falls on the body which its surface is rough (not flat), so the stream of paralles rays which fall on the body will be reflected to every direction.

Thanks for Your Attention