Physics - Sound & Electricity

• CRO


  Cathode ray oscilloscope
• Loudness


  • Human limit - 130db (db: decibels)
  • Reflection of sound forms echo
  • Uses: sonar (water), echolocation, ultrasound
• Speed


  Distance / time
• Static electricity


  Electrical energy due to accumulation of charges
• Current electricity


  Electrical energy due to the flow of charges
• Ways to charge an object with static


  • Contact - Rubbing (supplies energy for electrons to move)
  • No contact - Induced charging
• Types of lightning


  • Fork lighting
  • Sheet lightning
• What causes lightning


  1. Ice particles bump against cloud

  2. Electrons move to bottom of cloud

  3. Cloud induces a charge on the ground (only for fork lighting)

  4. Electric field and pathway is created

  5. Electrons travel to ground/cloud
• Basic circuit compounds


  • Battery (cell)
  • Lightbulb
  • Switch
• Requirements for a simple circuit

  • Energy source
  • Closed circuit
• What causes lightning


  1. Ice particles bump against cloud

  2. Electrons travel to bottom of cloud

  3. Cloud induces a charge on the ground

  4. Electrical field and pathway is created

  5. Electrons travel to ground or cloud
• Parts of the Ear

  • Ear canal - helps condense sound
  • Ear pinna - helps condense sound
  • Ear drum - allows vibrations to travel from gas to solid towards ossicles
  • Eustachian tube - relieves air pressure
  • Semi-circular canal - helps with balancing
  • Cochlea - sends vibrations to nerve endings
  • Nerves - sends electrical signals to the brain
  • Oval Window - transfers vibrations from solid to liquid to cochlea
• Echolocation


  Location of objects by reflected sound
• Induced Charging


  1. Bring charged object near A

  2. Place B next to A (touching)

  3. Electrons in A are repelled by charged object and move to B

  4. Bring B away

  5. A and B become oppositely charged
• Wooden block is to avoid grounding
• How does brush in Van De Graff transfer charges

  Slight contact of brush will cause electrons to flow to dome
• Frequency


  • 20hz - 20000hz
  • Below 20hz - infrasound
  • Above 20000hz - ultrasound