Homework

• What do all waves transfer without transferring matter?

  Energy
• How are oscillations or vibrations passed along in waves?


  Through the oscillations of particles instead of the particles themselves
• What are longitudinal waves characterized by?

  The direction of oscillations being parallel to the direction of energy transfer
• Give two examples of longitudinal waves.

  Sound waves and seismic P waves
• What does the 'P' in P waves stand for?

  Primary
• What are compressions and rarefactions in longitudinal waves?

  Compressions are where particles bunch up, and rarefactions are where they spread out
• How do transverse waves differ from longitudinal waves?

  The direction of oscillations is perpendicular to the direction of energy transfer
• Name two examples of transverse waves.

  Waves on the surface of water and seismic S waves
• Why are seismic S waves referred to as secondary waves?

  Because they are slower than P waves
• What is the definition of a waveform?

  A representation of any wave, including longitudinal waves
• What does the peak of a wave represent?

  The amplitude
• What is the symbol for wavelength and how is it measured?

  The symbol is Lambda (λ) and it is measured in meters
• What does the time period (T) of a wave represent?

  The time it takes for one complete wave to pass
• How is frequency defined in relation to waves?

  Frequency is how many waves pass a point every second
• What is the relationship between frequency and time period?

  They are reciprocals of each other
• How can you find frequency from a waveform?

  Measure the time period and then do one divided by that
• What is the wave equation?


  V = F λ (wave speed equals frequency times wavelength)
• How can you measure the speed of a wave using a ripple tank?

  Measure the distance between 10 peaks, divide by 10 to get the wavelength, then count the number of waves passing a point in ten seconds then divide by ten to record frequency. Use the wave equation.
• How can you measure the speed of sound waves using an oscilloscope?

  Clap next to a microphone, measure the time it takes for the sound to echo back, and use total distance divided by time
• What frequency range can the human ear hear?

  Between 20 Hz and 20 kHz (20,000 Hz)
• What is ultrasound?


  Any frequency above 20 kHz
• What happens when sound reaches a boundary between two different mediums?

  Some of it is transmitted while some is reflected
• How does ultrasound imaging work?

  A computer times how long it takes for ultrasound to return off different layers, building an image of what's inside
• What is sonar used for?

  To build up a picture of what's under a boat or around a submarine
• Why can P waves travel through liquids but S waves cannot?

  Because S waves are transverse and cannot move through liquids
• What does specular reflection mean?

  Reflection off a smooth surface without scattering
• What is the angle of incidence in reflection?

  The angle measured from the normal to the incoming wave
• What is diffuse reflection?


  Reflection off a rough surface that scatters light
• What is unique about electromagnetic (EM) waves?

  They do not need a medium to travel through
• What are the sections of the electromagnetic spectrum?

  Radio waves, microwaves, infrared radiation, visible light, ultraviolet, X-rays, gamma rays
• How are EM waves produced?

  When electrons lose energy, they emit EM waves
• What is the relationship between frequency and energy in EM waves?

  The higher the frequency, the more energy the wave carries
• Why are gamma rays considered dangerous?

  They are emitted by nuclei and involve a lot of energy
• What happens when high-energy EM waves like UV, X-rays, and gamma rays are absorbed by atoms?

  They can cause electrons to leave their atoms, leading to ionization
• What is a black body in physics?

  An object that perfectly absorbs and emits all wavelengths of radiation
• What happens to an object's temperature if it absorbs radiation at a greater rate than it emits?

  The temperature will increase
• What is refraction?


  A change in speed and direction of a wave when it moves from one medium to another
• How does light behave when it slows down in a new medium?

  It moves closer to the normal, resulting in a smaller angle of refraction
• How should angles be measured in relation to the normal?

  All angles are measured from the normal, which is perpendicular to the surface
• What is the principal focus of a convex lens?


  The point where rays of light converge