Waves

• What do all waves transfer without transferring matter?

  Energy
• How are longitudinal waves characterized in terms of oscillation direction?

  The direction of oscillations is parallel to the direction of energy transfer.
• What do we call the regions where particles bunch up in longitudinal waves?

  Compressions
• What do we call the regions where particles are spread out in longitudinal waves?

  Rarefactions
• How are transverse waves characterized in terms of oscillation direction?

  The direction of oscillations is perpendicular to the direction of energy transfer.
• What is a waveform and what does it represent?

  • A graphical representation of a wave
  • Displacement is on the y-axis
  • Time or distance is on the x-axis
• What is the peak of a wave called?

  Amplitude
• What does the amplitude of a wave represent?

  The maximum displacement from equilibrium.
• What symbol is used to represent wavelength?

  Lambda (λ)
• How is the time period of a wave defined?

  It is the time it takes for one complete wave to pass a point.
• What is frequency in the context of waves?

  How many waves pass a point every second.
• What is the formula for frequency?


  Frequency (f) is equal to \( \frac{1}{\text{Time period (T)}} \).
• How can you find frequency from a waveform?

  Measure the time period and then calculate \( f = \frac{1}{T} \).
• What is the wave equation?

  The wave equation is \( V = f \cdot λ \), where V is wave speed, f is frequency, and λ is wavelength.
• What is the range of visible light wavelengths?

  Approximately 400 to 750 nm.
• How does the intensity of a wave relate to its amplitude?

  The intensity is proportional to the amplitude squared.
• What happens to light waves when they move from one medium to another?

  They change speed and wavelength, and may change direction (refraction).
• What is refraction?


  Refraction is the change in direction of a wave as it passes from one medium to another.
• How does the angle of refraction compare to the angle of incidence when light slows down?

  The angle of refraction is smaller than the angle of incidence.
• What is the refractive index symbol?

  n
• How is the refractive index calculated?

  It is the ratio of the speed of light in a vacuum to the speed of light in the medium.
• What does Snell's law describe?

  It describes the relationship between the angles of incidence and refraction and the refractive indices of two media.
• What happens to blue light's refractive index compared to red light's in the same medium?

  Blue light's refractive index is higher than red light's.
• What is dispersion in the context of light?

  Dispersion is the separation of light into its component colors due to varying refractive indices.
• What is the critical angle?

  The critical angle is the angle of incidence that results in an angle of refraction of 90°.
• What occurs when the angle of incidence exceeds the critical angle?

  No light is refracted out of the medium; all light is reflected back inside.
• How is the critical angle calculated using Snell's law?


  By using the equation \( \sin \Theta_c = \frac{n_2}{n_1} \).
• How do optical fibers work?

  • Basic optical fiber consists of a glass core and a protective sheath.
  • The cladding has a lower refractive index than the core.
  • Total internal reflection occurs due to the refractive index difference.
• What is modal dispersion in optical fibers?

  It is the spreading of light as it travels down a fiber, causing different paths and times to reach the end.
• What is pulse broadening in optical fibers?

  It occurs when light pulses stretch too much and start to overlap.
• What are some methods to mitigate pulse broadening in optical fibers?

  1. Make the fiber thinner to reduce light divergence.
  2. Use repeaters to retransmit broadened pulses.
  3. Utilize graded index fibers.
• How do lenses use refraction?

  Lenses use refraction to make rays of light converge or diverge.
• What is the principal focus of a convex lens?


  It is the point where rays of light converge.
• What is the focal length of a lens?

  The distance from the center of the lens to the principal focus.
• How is an image formed by a convex lens?

  By drawing two rays: one through the center and one parallel to the principal axis that passes through the principal focus.
• What happens to the image when the object is very close to a convex lens?


  The image cannot be projected but is magnified and virtual.
• What type of image do concave lenses produce?

  Concave lenses always produce a virtual image.
• What is the power of a lens?

  The reciprocal of the focal length, measured in diopters.
• How do you calculate the total power of thin lenses used together?

  It is the sum of the individual powers of the lenses.
• What is the full lens equation?

  The full lens equation is \( \frac{1}{f} = \frac{1}{U} + \frac{1}{V} \).