Physics: waves: P12

Physics: waves: P12

1. Transverse waves

   • Waves that have oscillations and particles which travel perpendicular to the direction of energy travel.
     • travel at the same speed through a vacuum

2. longitudinal

   • Waves that have oscillations which travel parallel to the direction of energy travel. (They travel straight).

3. EM SPECTRUM:

   • Waves on the spectrum, in order: radio-waves, microwaves, infrared, visible light, ultraviolet, x-rays and gamma radiation
   • uses
     • radiowaves: television signals
     • microwaves: cooking, mobile phones
     • infrared: optical fibre communication
     • visible light: seeing
     • ultraviolet: detecting forged bank notes
     • x-rays: medical images of bones
     • gamma radiation: killing cancer cells
   • Electromagnetic waves are waves that can travel through the vacuum of outer space. Mechanical waves are opposite to this, as they require a medium to travel through.
     • Vacuum is a space that is entirely devoid of any matter
   • Connected to physics because EM waves are a type of energy that construct the world and outer space especially.
     • Connected to my life as many types of these waves are present constantly (e.g. visible light, microwaves, radiowaves).

4. How do sound waves travel to the ear and allow us to hear?

   • Sound waves travel to the ear, through the ear canal and then to the ear drum, causing vibrations.
     • The human hearing range is 20Hz to 20kHz
     • In addition, nerve cells/ hairs in the cochlea send sound signals to the brain. Deafness is caused by damage to the nerve cells.

5. What are waves?

   • Vibrations that transfer energy from one place to another, without transferring matter.

6. Wave speed calculations:

   • speed = distance/ time
   • speed= wavelength x frequency

7. ECHOES:

   • Sound waves that have been reflected from a surface.

8. Speed of light is 300,000,000 m/s, 186,282 miles and 299, 792 km

   • First considered by Oluas Roemor, who calculated 140,000 miles per second through an interesting method of observing light from Jupiter around orbit.

9. Earth's structure:

   • inner core, outer core, mantle, crust