P6

• Optics


  A branch of physics that deals with the study of light and its interactions with matter
• Optics


  • Encompasses the behavior, properties, and manipulation of light, as well as its interactions with various optical devices and systems
• Topics in Optics


  • Mirrors
  • Light as an Electromagnetic Wave
  • Refraction
  • Reflection
  • Dispersion
  • Polarization

  
• Hans Christian Ørsted


  Discovered the connection between electric currents and magnetic force
• André-Marie Ampère


  Formulated Ampère's law, relating currents to magnetic effects
• Michael Faraday


  Discovered electromagnetic induction
• When a charged particle moves, it creates an electric current and a magnetic field

  
• If the charges move back and forth (AC), the direction of the current and the magnetic field changes accordingly
• Faraday's law


  A changing magnetic field generates an electric field
• James Clerk Maxwell


  Scottish mathematician and scientist responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism, and light as different manifestations of the same phenomenon
• Maxwell's Equations


  A set of four fundamental equations describing the behavior of electric and magnetic fields and their interaction with electric charges and currents
• Maxwell's equations described how changing electric and magnetic fields influenced each other, leading Maxwell to conclude that oscillating electric and magnetic fields could propagate through space in the form of waves
• Electromagnetic (EM) Waves


  Changing electric and magnetic fields, transporting energy and momentum through space
• Wavelength (λ)


  The distance between identical points on a wave for one wave cycle
• Frequency (f)


  The number of waves that pass a given point for a given amount of time
• A higher frequency corresponds to higher energy and a lower frequency corresponds to lower energy
• Maxwell realized that the speed of electromagnetic waves matched the experimentally determined speed of light, leading him to propose that light is an electromagnetic wave
• Heinrich Hertz


  German physicist who conducted experiments to observe and analyze the properties of the generated and detected electromagnetic waves, providing compelling evidence that electromagnetic waves exhibited similar properties to light waves
• Electromagnetic Spectrum


  • Radio waves
  • Microwaves
  • Infrared
  • Visible light
  • Ultraviolet
  • X-rays
  • Gamma rays

  
• The electromagnetic spectrum extends from the longest wavelengths of radio waves up to the high frequencies of gamma rays
• Refraction


  The bending of light as it crosses over from one medium to another

  
• Refractive Index


  Measures the bending of a ray of light when passing from one medium into another

  
• Law of Refraction (Snell's Law)


  Describes how light bends when it passes from one medium to another

  
• Light bends towards the normal when going from a lower to a higher refractive index and away from the normal when going from a higher to a lower refractive index

  
• Sample Problem: Determining the index of refraction of alcohol


  1. Shine light ray at 45o to the surface of alcohol

  2. Light ray bends to 22o to the normal

  3. Use Snell's law to calculate the index of refraction of alcohol
• Sample Problem: Light traveling through an optical fiber


  1. Determine the angle of refraction when light exits the fiber into air at an angle of incidence of 30o

  2. Determine the angle of refraction when the angle of incidence is 50o

  
• Total Internal Reflection


  The phenomenon where light is reflected back into the medium when the angle of incidence is greater than the critical angle

  
• Conditions for total internal reflection: 1) Light ray moves from a more optically dense medium to a less optically dense medium, 2) Angle of incidence is greater than the critical angle

  
• Sample Problem: Determining the refractive index of the cladding in an optical fiber


  Given the refractive index of the core, find the refractive index of the cladding such that the critical angle between the two is 80o

  
• Reflection


  The phenomenon of bouncing back of light or other forms of electromagnetic radiation when it encounters a surface
• Law of Reflection


  The angle of incidence is equal to the angle of reflection, and the incident ray, the normal, and the reflected ray all lie in the same plane
• Sample Problem: Determining the angle of reflection


  1. Light is incident on a flat surface at an angle of 10o

  2. Find the angle of incidence

  3. Find the angle of reflection

  4. Sketch the path of the reflected beam
• Specular Reflection


  Reflection off a smooth surface where the reflected rays maintain their parallel nature

  
• Diffuse Reflection


  Reflection off a rough or irregular surface where the reflected rays scatter in different directions