2. 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.
3. 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
4. Bodies that can spread light is
called light source. While bodies
that cannot spread light theirself is
called dark body.
6. Are these light sources?
moon
water
mirror
These items are not light sources, instead they
are reflecting light from other sources.
7. light
source
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.
8. Light Reflection
Angle of incidence
Angle of reflection
The ‘angle of
reflection’ is
always equal
to the ‘angel
of incidence’.
r = i
If a light hits a
body surface
commonly will
be reflected.
9. Law of Reflection
• Incident angle, normal line and
reflected ray lie on one flat plane
• Incidence angle is equal to reflected
angle (i=r)
10. 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.
light
source
light
source
11. Specular Reflection
Reflection ray
Incidence 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.
12. 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.
