Topic 4 - Waves.

• Waves transfer energy and information without transferring matter.
• When particles travel, they do not carry anything with them. They leave the substance they came from. Example, travelling through water, they do not carry water particles.
• What is frequency in waves?

  The number of complete cycles passing a certain point per second.
• What is the formula for frequency?

  Frequency = wavelength / speed
• What is the wavelength of a wave?

  The length of a full wave.

  A) here

  
• What is a transverse wave?

  A transverse wave is a type of wave in which the particles of the medium vibrate perpendicular to the direction of wave oscillation.

  
• What is a Longitudinal wave?


  Vibrations that are parallel to the direction (same direction it is facing).

  
• What are examples of transverse waves?

  Light, S-waves and water ripples.
• What are examples of Longitudinal waves?

  Sound waves, spring and P-waves.
• What is the formula for wave speed?

  Wave speed = frequency x wavelength

  
• What is the formula for wave speed when you have distance?

  Wave speed = distance / time.

  
• How do you measure sound traveling in the air?

  1. Setup: Place two microphones at a known distance in an obstacle-free environment.
  2. Source: Generate a sharp sound near the microphones.
  3. Recording: Record the time for the sound wave to reach each microphone with precise timing.
  4. Calculation: Use the formula velocity = distance/time to find the speed of sound.
• How to measure the speed of water ripples?

  1. Use a signal generator
  2. Turn on the strobe light to help see the waves
  3. Alter the frequency of the strobe light
  4. Measure the distances between the lights of the waves
  5. use the formula: wave speed = Frequency * wavelength.
• What is the effect of reflection on waves?

  Bouncing back of waves when they encounter a boundary.
• What is the effect of refraction on waves?


  Change in direction and speed, causing the wave to deviate. This can be due to density that alters the wave speed.
• What is the effect of transmission on waves?

  
Continuation of the wave in the new medium without reflection or refraction.
• What is the effect of absorption on waves?

  Conversion of wave energy into other forms within a material. Often converted into thermal energy.
• When waves encounter a boundary between two different mediums, such as air and water or glass and air, they may undergo refraction. Refraction involves a change in the direction and speed of the waves as they transition from one medium to another.
• Different substances may absorb, transmit, refract, or reflect waves in ways that vary with wavelength.
• What are sound waves?

  Longitudinal waves that are caused by vibrations at a certain frequency.
• An object's SIZE, SHAPE & STRUCTURE determine the frequencies of sound they transmit.
• How is sound registered by your ear?

  Sound vibrates to your eardrums --> ossicles --> auditory nerve which transmits the vibrations into electrical signals that can be interpreted by the brain.
• What is the hearing range of your ear?

  20 Hz to 20,000 Hz.
• Sound with frequencies less than 20 hertz, Hz, is known as infrasound
• Sounds above 20,000 Hz are ultrasound.
• Uses of ultrasound:

  • Sonar:
  • Application: Underwater navigation, object detection.
  • Mechanism: Ultrasound waves emitted; echoes used for distance calculation.
  • Foetal Scanning:
  • Application: Medical imaging during pregnancy.
  • Mechanism: Ultrasound waves create echoes for real-time foetal imaging.
• Uses of infrasound:

  • Monitoring Natural Events:
  • Application: Detecting earthquakes and volcanic eruptions.
  • Animal Communication:
  • Application: Studying communication in animals like elephants.
• S-waves are transverse and P-waves are longitudinal. This means that P-waves are faster than S-waves. This helps in the detection of earthquakes.