reflection and refraction

• Reflection is the bouncing back of light when it strikes a reflecting surface.
• The ray that strikes the surface is called the incident ray.
• The ray that rebounds from the surface is called the reflected ray
• A line perpendicular to the surface at the point of incidence is called the normal.
• The angle between the incident ray and the normal is called the angle of incidence, this is represented as θ
• the angle between the reflected ray and the normal is called the angle of reflection, this is also represented by θ
• The angle between the reflected ray and the normal is called the angle of reflection, represented as θr.
• The angle between the incident ray and the normal is called the angle of incidence, this is represented as θi.
• The law of reflection states that the angle of reflection equals the angle of incidence.
• mirror- It is any surface that is smooth enough to produce regular reflection of light incident upon it.
• A plane mirror is one with flat surface.
• A spherical mirror is a mirror whose reflecting surface is taken from the surface of a sphere. A spherical mirror maybe concave or convex.
• When a sheet of paper is illuminated with many parallel incident rays, it can be seen at many different angles, because its surface is rough and diffuses the light.
• A mirror illuminated by many parallel rays reflects them in only one direction, because its surface is very smooth.
• Moonlight is spread out when it is reflected by the lake, because the surface is shiny but uneven.
• real image- It is formed by actual intersection of light rays after encountering a mirror. A real image is formed in front of the mirror
• real images- it can be projected on a screen.
• real images- It is always inverted.
• virtual images- No light passes at the apparent location of the image. The apparent location of the image is found by extending the reflected rays until they intersect. A Virtual image is formed at the back of the mirror.
• virtual images- It cannot be focused on a screen.
• virtual images- It is always upright.
• Optical density has something to do with the transparency of a substance to light.
• Light travels slowly in an optically dense

  substance.
• A ray of light moves closer to the perpendicular when entering a medium with a higher index of refraction
• A ray of light moves closer to the perpendicular when entering a medium with a higher index of refraction
• Concave Lenses- For any distance from the lens, the image formed by a concave lens is virtual, upright, smaller than the object, and located on the same side of the lens as the

  object.
• Convex Lenses- it should be noted that concave lenses form the same kind of image as convex mirrors. On the other hand, convex lenses form the same kinds of image as concave mirrors.
• White light is a uniform mixture of all visible wavelengths.
• Dispersion- spreading of white light into its full spectrum of wavelengths.
• dispersion occurs whenever the propagation of light depends on wavelength.
• refraction- responsible for dispersion in rainbows and many other

  situations.
• we know that the index of refraction n depends on the medium.
• A sequence of red to violet is produced, because the index of refraction increases steadily with decreasing wavelength.
• Color addition is the process of producing other colors by mixing suitable portions of the primary colors of light. The primary colors of light are red, blue, and green.
• Red + Blue + Green = White

  red + Blue = Magenta

  Blue + Green = Cyan
• secondary colors- All other colors produced by mixing suitable portions of primary colors
• colors opposite each other are complementary.
• Complementary colors, when added, produce white.
• The property of wave that distinguishes transverse waves from longitudinal waves is Polarization
• Only transverse waves can be polarized,