Phys 2

• What do all types of radiation have in common?

  Speed
• How can you tell one form of electromagnetic energy from another?

  Wavelength
• On rotating the analyzer if the intensity of light rays coming out of it varies from maximum to zero, then the incident beam of light is

  Partially polarized
• Which one of the following cannot be polarized?

  sound waves
• Light waves are

  transverse
• The speed of light is closest to

  300,000,000 m/s
• The region of the electromagnetic spectrum where humans can detect electromagnetic radiation is

  Visible
• It is a law that applies only if the incident light passing through the analyzer is nearly polarized.

  Malus's Law of
• What is polarized light

  when waves oscillates in one direction
• A polarized light of intensity lo is passed through another polarizer whose pass axis makes an angle of 600 with the pass axis of the former. What is the intensity of emergent polarized light from second polarizer?

  I=Io/4
• The number of crests that pass a given point within one second is described as the frequency
• The distance between crests is the wavelength
• An electromagnetic wave can also be described in terms of its energy in units of measure called electron volts (eV).
• This range of wavelengths is now known as the "electromagnetic spectrum."
• The permittivity of free space is also known as the "electric constant and describes the strength of the electrical force between two charged particles in a vacuum.
• The permeability of free space is the magnetic analogue of the electric constant
• It describes the strength of the magnetic force on an object in a magnetic field.
• Polish-American physicist Albert Michelson made a very precise measurement of the speed of light that was in extremely close agreement with Maxwell's predicted value.
• All electromagnetic waves:

  • transfer energy from the source of the waves to an absorber.
  • can travel through a vacuum such as in space.
  • all travel at the same velocity through a vacuum.
• • Electromagnetic waves form a continuous spectrum of waves. This includes:
  • waves with a very short wavelength, high frequency and high energy
  • waves with a very long wavelength, low frequency and low energy
• violet light has the highest frequencies of visible light
• red light has the lowest frequencies of visible light
• When a beam of light passes through a prism, a person can see each colour of the rainbow separated into their individual wavelengths.
• Reflection of a light wave involves the bouncing of a light wave off the boundary
• refraction of a light wave involves the bending of the path of a light wave upon crossing a boundary and entering a new medium
• The fundamental law that governs the reflection of light is called the law of reflection.
• The law of reflection states that "When a light ray reflects off a surface, the angle of incidence is equal to the angle of reflection.'
• The fundamental law that governs the refraction of light is Snell's Law.
• Snell's Law states that "When a light ray is transmitted into a new medium, the relationship between the angle of incidence ($\theta$) and the angle of refraction ($\theta_r$) is given by the following equation: $n_i sine(i) =$$n_r sine(r)$
• Total internal reflection (TIR) is the reflection of the total amount of incident light at the boundary between two media.
• Remember, there are two necessary conditions for total internal reflection do happen: the ray of light must be traveling from a dense medium to a rare medium. the angle of incidence must be greater than the critical angle.
• Polarizers are usually made out of oblong shaped molecules, all aligned in the same direction
• If the polarization is perpendicular to the long axis of molecules, then it is transmitted almost entirely and that direction is the axis of the polarizer.
• Malus Law Formula

  The intensity (I) of polarized light after passing through a polarizing filter is usually measured in. The light intensity, which passes through the ideal polarizer can be calculated as:

  $I=$$I_Ocos^2$
• Maxwell's calculation of the speed of an electromagnetic wave included two important constants: the permittivity and permeability of free space.
• Maxwell's prediction of electromagnetic waves resulted from his formulation of a complete and symmetric theory of electricity and magnetism, known as Maxwell's equations.
• The intensity of light transmitted through the analyzer is given by Malus' law
• Three polarized are placed such that, the first and the third are mutually perpendicular to each other. Unpolarized light of intensity / is incident or first polarized. The intensity of light emerging from the third polaroid's is (1/16) of the intensity of incident light. Find the angle between first the angle between first and second polaroid's

  24.5°
• For our purposes, it is sufficient to merely say that an electromagnetic wave is a transverse wave that has both an

  electric and a magnetic component
• The use of two filters, one can completely block all of the light that is incident upon the set; this will only occur if the polarization axes are rotated such that they are:

  perpendicular to each other