4.6 Waves

4.6 Waves

1. Definition

   • Transverse
     • a wave in which the medium vibrates at right angles to the direction of its propagation.
   • Longitudinal
     • running lengthwise rather than across.
   • Electromagnetic waves
     • list

2. How to measure the speed of sound in air

   • two people (person A and person B) are placed a distance apart, eg 100 metres
     • person A fires a starter’s pistol
       • person B times the difference between seeing the flash of the gun and hearing the sound - this is measured in seconds

3. the two types of seismic wave produced by earthquakes

   • Body waves
     • P-waves
   • Surface waves
     • S-waves

4. processes which convert wave disturbances between sound waves and vibrations in solids

   • Sound waves can travel through solids causing vibrations within the solid
     • Sound going to ear drums those vibrating which vibrates the bone attached to the ear

5. How to measure the speed of ripples on a water surface

6. Describe how echo sounding using high frequency sound waves is used to detect objects in deep water and measure water depth

   • The time between a pulse of sound being transmitted and detected and the speed of sound in water can be used to calculate the distance of the reflecting surface or object. The process is very similar to ultrasound imaging.

7. changes in atoms and the nuclei of atoms can result in electromagnetic waves being generated or absorbed.

   • Gamma rays are produced by changes in the nucleus of an atom. They are a form of nuclear radiation. High energy waves such as X-rays and gamma rays are transmitted through body tissues with very little absorption.

8. why an opaque object has a particular colour, with reference to the wavelengths emitted

   • Opaque objects do not transmit visible light so certain wavelengths are absorbed and others are reflected

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