Waves -Gcse Physics

• A transverse wave - ossilations travel perpendicular to energy transfer, light and water waves, electromagnetic wave and s wave
• Longitudinal wave - ossilations travel parallel to the energy transfer, sound waves and p waves
• The two speed equations are speed (s)= distance/time and velocity = wavelength * frequency
• Refracting- when a wave travels through a new material and changes speed due to change in density
• Reflect - when wave bounces back in the same direction
• When treating cancer with radiation

  Radiation is targeted at cancer cells to kill them, while trying to avoid healthy cells
• Electromagnetic spectrum

  • Radio waves
  • Microwaves
  • Infrared
  • Visible light
  • Ultraviolet
  • X-rays
  • Gamma rays
• Ultraviolet


  • Absorbed by visible light, which is then emitted, making it energy efficient
  • Used in fluorescent lamps
  • Used to detect forgeries in bank notes and passports
  • Used to sterilise water and kill bacteria
• Gamma rays

  • Produced by changes in the nucleus of an atom
  • Used in some medical imaging techniques to detect cancer
  • Used in cancer treatments to target and kill cancer cells
• Microwaves


  • They pass through earths watery atmosphere
  • Satellite TV signal from transmitter is transmitted into space
  • Picked up by satellite reciever dish orbiting thousands km above earth
  • Satelite transmits the signal back to earth in diff direction
  • Recieved by satellite dish on ground
• Microwaves


  • RF+heat up food
  • Microwaves are absorbed by water molecules in food
  • Transferred to other water molecules to heat food up
• X Ray

  • view internal structure of objects and materials (our bodies)
  • Radiographs in hospital use x-ray to detect broken bones - the x-ray is transmitted by flesh but absorbed by dense material (bones)
• Infared radiation

  • hot things give this out ( hotter objects give out more)
  • infared cameras - monitor temp and detect infrared radiation
  • Thermal imaging - camera detects IR and turns it into electrical signals that are then displayed on a screen as a picture ( also used by police to find people hiding in the dark)
  • Cooking food
  • structure of the earth
  • used in security systems
  • transfer information for devices and tv remotes
• Radio waves

  • produced by alternating current in a wire
  • cook food
  • communication - to satellites and to other countries
  • long waves - received halfway across the earth
  • short waves - reflected by earths atmosphere to travel across the earth
• Graphite moderators


  • Slow down the fast moving neutrons
• Nuclear fission splitting up of big automic particle 1. slow moving neutron fired at large unstable nucleus

  2. Neutron absorbed by nucleus

  3. Nucleus becomes more unstable and splits

  4. it releases 2/3 neutrons released

  5. Nucleus splits to form 2 daughter nuclei
• Measure speed of waves

  • connect single generator to speaker and generate a sound at a specific frequency
  • connect two microphones to an oscilloscope so waves are detected at each microphone and displayed seperately on oscilloscope
  • place microphones near each other in front of speaker ( waves should be aligned) slowly move microphones away from speaker until two wave forms on the oscilloscope
  • measure the distance and note the frequency use wave speed = frequency x wavelength
  • to be more accurate repeat for different frequencies and calculate the mean
• Control Rods

  limit rate of reaction by absorbing the excess neutrons. These can be lowered or raised
• Nuclear fusion

  joining of small nuclie

  1. two small light nuclei collide at high speed and fuse to create a large heavier nucleus
  2. This only happens at really high pressures due to the strong bonds of electrostatic repulsion
  3. some of the mass of lighter nuclei convert to energy
• measure speed of water ripples using strobe light

  1. using a single generator attach a dipper to a ripple tank and set at a frequency and put a piece of paper under tank
  2. dim lights and turn strobe lamp on until you see a wave pattern ( shadow of wave peak)
  3. alter frequency of strobe light until pattern appears to freeze (when frequency of wave and strobe light equal)
  4. measure the distance of shadow line 10 and divide by 10 as your wavelength
  5. use the equation v = frequency x wavelength
• Measure frequency of sound waves through a hit object

  1. measure and record the length of metal rod
  2. set up equipment (clamp,elastic band, rod, hammer, microphone)
  3. tap rod with hammer and write down frequency using an app
  4. repeat 3 times to find average
  5. use v = f x wavelength ( remember to multiple your rod distance by 2)