Waves

• What is the definition of wavelength?

  Distance between the same points on two consecutive waves
• How is amplitude defined?

  Distance from equilibrium line to the maximum displacement (crest or trough)
• What does frequency measure?

  The number of waves that pass a single point per second
• What is the period of a wave?

  The time taken for a whole wave to completely pass a single point
• How do you calculate wave velocity?

  Velocity = frequency × wavelength, or $v =$$f \lambda$
• What is the formula for period?

  Period = $\frac{1}{frequency} =$$T =$$\frac{1}{f}$
• What happens to velocity when frequency increases?

  Velocity increases
• What is the relationship between wavelength and velocity?

  If wavelength increases, velocity increases
• How is period related to frequency?

  Period is inversely proportional to frequency
• What does a smaller period indicate about frequency and velocity?

  A smaller period indicates higher frequency and greater velocity
• What are the two main types of waves?

  • Transverse waves
  • Example: Light, electromagnetic waves
  • Vibrations are at right angles to the direction of travel
  • Longitudinal waves
  • Example: Sound waves
  • Vibrations are in the same direction as the direction of travel
• What happens to the medium when a wave travels through it?

  The wave moves, not whatever it passes through

  
• How can you measure the velocity of sound in air using an echo?

  Make a noise at ~50m from a solid wall and record the time for the echo to be heard, then use speed = distance/time
• How can you measure the velocity of sound using two microphones?

  Connect two microphones to a datalogger at a large distance apart and record the time difference between a sound passing one to the other, then use speed = distance/time
• How can you measure the velocity of ripples on water surface?

  Use a stroboscope with the same frequency as the water waves, then measure the distance between the ‘fixed’ ripples and use $v =$$f \lambda$
• How can you measure wave speed by drawing a line?

  Move a pencil along the paper at the same speed as a wavefront and measure the time taken to draw this line, then use speed = distance/time
• What are the three interactions of waves at the boundary between two different materials?

  • Reflection
  • Absorption
  • Transmission
• What happens to waves when they reflect off a flat surface?

  Waves will reflect off a flat surface
• How does the smoothness of a surface affect wave reflection?

  The smoother the surface, the stronger the reflected wave is
• What happens when waves hit a rough surface?

  Rough surfaces scatter the light in all directions
• What is the law of reflection?

  The angle of incidence equals the angle of reflection

  
• When will light reflect off an object?

  Light will reflect if the object is opaque and is not absorbed by the material
• What happens to light energy when it is absorbed by electrons?

  The electrons absorb the light energy and then reemit it as a reflected wave
• What occurs during transmission of waves?

  Waves will pass through a transparent material
• How does transparency affect wave transmission?

  The more transparent the material, the more light will pass through
• What is absorption in terms of wave interaction?

  If the frequency of light matches the energy levels of the electrons, the light will be absorbed
• What happens to absorbed light energy over time?

  Absorbed light energy is reemitted over time as heat
• What does it mean if a material appears green?

  Only green light has been reflected, and the rest of the frequencies in visible light have been absorbed
• How do sound waves travel through solids?

  Sound waves can travel through solids causing vibrations in the solid
• What role does the outer ear play in hearing?

  The outer ear collects the sound and channels it down the ear canal
• What happens to sound waves as they travel down the ear canal?

  They still remain a pressure air wave
• What occurs when sound waves hit the eardrum?

  The eardrum vibrates as the incoming pressure waves reach it
• How does the eardrum respond to compression and rarefaction?

  Compression forces the eardrum inward, and rarefaction forces it outward
• At what frequency does the eardrum vibrate?

  The eardrum vibrates at the same frequency as the sound wave
• How do the small bones in the ear respond to sound?

  The small bones connected to the eardrum also vibrate at the same frequency
• What happens to vibrations of the bones in the ear?

  They are transmitted to the fluid in the inner ear
• How are compression waves transferred to the fluid in the cochlea?

  Compression waves are transferred to the fluid in the cochlea
• What role do the small bones play in sound transmission?

  The small bones act as an amplifier of the sound waves the eardrum receives
• How do the small hairs in the cochlea respond to sound?

  Each hair is sensitive to different sound frequencies, moving more for certain frequencies
• What happens when a certain frequency is received by the cochlea hairs?

  The hair attuned to that specific frequency moves a lot, releasing an electrical impulse to the brain