Waves: Topic Overview

Waves: Topic Overview

1. What Waves Do:

   • Carry energy
     • transfer of energy but the particles don't move with the energy
     • Higher frequency waves carry more energy
   • particles can move or vibrate
     • up and down
     • side to side

2. Types of Waves

   • Transverse
     • the particles vibrate at right angles to the direction of the energy
     • E.g. light, water wave
   • Longitudinal or compression
     • vibrate backwards and forwards in the same direction as the transfer of energy
     • E.g sound wave

3. Electromagnetic Spectrum

   • Gamma Rays
     • high energy
     • released from substances that are radioactive
     • detected by a Geiger counter or photographic film
     • used to kill cancer cells
   • X-rays
     • produced when fast-moving electrons lose energy suddenly
     • used in x-rays
     • shorter wavelength x-rays are more penetrating
   • Ultraviolet
     • causes sunburn
     • used to kill bacteria
     • from the sun
   • Infra-Red (IR)
     • have a frequency lower than red light (visible)
     • released from vibrating atoms and molecules
     • all objects produce some level of IR
   • Microwaves
     • generated by vibrating electrons in electronic devices

4. Properties/ Feautres of waves

   • Frequency (f)
     • Number of waves passing a point a second
     • Measured in Hertz( Hz) or cycles (waves) per second
   • Wavelength
     • The distance between two successive points on a wave
   • Amplitude
     • the distance from the midpoint (or normal) of a wave to its highest or lowest point
     • Measured in mm,cm or m
     • In sound waves: higher amplitude = louder
   • Period
     • Time for one wave to pass a point
     • Usually measured in seconds
   • Speed or velocity
     • can be calculated using: speed= frequency x wavelength
     • The speed of all electromagnetic waves is 3 x 10(8) m/s