2. Light (along with all other forms of electromagnetic
radiation) is a fundamental entity and physics is
still snuggling to understand it.
Light may be defined as electromagnetic radiation,
which is visible to the human eye. It is also applied to
radiation having frequencies somewhat above and
below the range human sight.
Many of the properties of light can be explained on
the theory that light is a transverse wave motion
with both electrical and magnetic properties. This
theory satisfactorily explains the variation in the
velocity of light as it passes through different
solid, liquids, and gases.

7. It is a line drawn perpendicular to a line or
plane.
It is the angle between the incident ray and
the normal drawn to the point of reflection.

8. the angle between the reflected ray and the
normal drawn to the point of reflection.
the incident ray, reflected ray, and normal
to the surface all lie in the same plane

9. It is the ray that represents the light
reflected by the surface.
It is a ray of light that strikes a surface.

10. surface normal
Incident ray
Reflected ray
Angle of Angle of
incidence reflection
90°
Point of incidence
plane reflecting surface

16. reflected ray
Incident ray
normal
r
i
boundary
R
reflected ray
air
glass

22. Substances
Index of refraction (n)
Vacuum
1.0000
Air (0°C, 101 kPa)
1.0003
Water
1.33
Ethyl alcohol
1.36
Quartz (fused)
1.46
Glycerin
1.47
Lucite or Plexiglass
1.51
Glass (crown)
1.52
Sodium chloride
1.53
Glass (crystal)
1.54
Ruby
1.54
Glass (flint)
1.65
Zircon
1.92
Diamond
2.42