TIR and lenses

• Intensity equation


  I = P / A
• What is the refractive index of a material through which light travels as a speed of v


  n = c / v
• What is the critical angle


  The angle of incidence for which the angle of refraction is 90 degrees and all the light passes along the boundry between the mediums, beyond this angle all light will be reflected
• Critical angle equation


  SinC = 1 / n
• What is total internal reflection


  Total internal reflection is where all the light is reflected back at a boundry between two mediums, it occurs when light is incident at an angle greater than the critical angle
• What is the focal point of a converging lens


  The single point where the parallel rays of light entering the lens converge to
• What is the focal length of a lens


  The distance between the centre of the lens and the focal point
• Power of a lens equation


  Power = 1 / focal length
• Total power of a combination of thin lens


  P = P1 + P2 + P3 + ...
• What is a real image


  A real image is one that can be projected onto a screen and is always inverted
• What is a virtual image


  Virtual images are the consequence of rays of light appearing to meet at a point, they cant be projected onto a screen
• Magnification equation


  Magnification = Image height / object height
• What is plane polarisation


  When the oscillations of a wave are restricted to a single plane
• What is Huygen's principle


  Every point on the wavefront act as a secondary source of spherical wavelets