Physics gcse sp4

• A wave is an oscillation (vibration) that transfers energy and information but not matter.
• Waves can either be transverse or longitudinal.
• Longitudinal waves are waves where the vibrations are parallel to the direction of travel, such as sound waves through air
• Transverse waves are waves where the vibrations are at right angles to the direction of travel, such as water waves on a pond
• The speed of a wave depends on its frequency and wavelength according to the equation v=fλ
• An example of a longitudinal wave is a sound wave.
• When waves travel through a medium such as air or water the particles vibrate in the same direction
• Ripples on the water surface cause floating objects like twigs to bob up and down. They don’t move the object across the water to The edge. This is evidence that the wave travels not the water
• A transverse wave has crests and troughs which are perpendicular to the direction of energy transfer
• Reflection occurs because the wavefront hits something solid and cannot pass through it. Instead, the wavefront bounces back
• Waves can be reflected when they hit an obstacle. When this happens some of the energy from the wave is transferred back into the original medium (e.g. light bouncing off a mirror)
• In a longitudinal wave there are compressions and rarefactions which are parallel to the direction of energy transfer
• Sound waves can be reflected by walls, ceilings and floors. Sound waves from different sources can interfere with one another when they meet at an obstacle
• Sound waves can be heard when they reach our ear drum
• Waves can be reflected by surfaces such as walls or mirrors
• The angle between the incident ray and normal line is equal to the angle between the reflected ray and normal line
• Sound waves need a material medium to travel through so they cannot travel through space without any matter present
• wavefronts are imaginary lines that pass through a point on the wavefront
• Wavefronts are imaginary lines drawn through identical points on waves
• Wavefront diagrams can be used to represent a wave. The distance between each wavefront is equal to the wavelength of the wave.
• The amplitude is the maximum displacement of a point from its rest position.
• The wavelength is the distance between two adjacent points on a wave.
• The frequency is the number of waves passing a point per second. It is measured in Hertz (Hz)
• The period of a wave is the amount of time it takes for a full cycle of the wave to be completed. In other words it’s the length of time it takes for one complete wave to pass a point
• the formula for a period of a wave is 1/frequency
• Sound travels faster through solids than liquids or gases because particles in solids vibrate more easily due to being closer together.
• Wave speed is how fast a wave moves or how fast it transfers energy or information.
• Speed of a wave is v=x/t
• Wave velocity is the speed of the wave in certain direction
• Reflected waves are waves that are reflected from a boundary between two different mediums.
• distance of reflected waves= total distance travelled/2
• The angle of incidence is equal to the angle of reflection (law of reflection)
• Speed of sound in air is 330m/s
• sound can be measured using a decibel meter or by measuring amplitude with an oscilloscope
• Waves transfer energy and information but they do not transfer matter
• Examples of transverse waves are

  • ripples on the surface of water.
  • vibrations in a guitar string.
  • all electromagnetic waves
  • light waves
• • Examples of longitudinal waves are:
  • Tsunami waves,
  • seismic-P waves,
  • sound waves
• particles in Transverse waves are perpendicular to the direction to the energy transfer. Whereas particles in longitudinal waves oscillate in the same direction of the energy transfer
• speed=distance/time distance=speed x time time=speed x distance
• Wave speed= frequency x wavelength (m/s)