Waves

Waves

1. Definitions

   • Amplitude (A) - This is "how high the wave is.
   • Wavelength (λ) - this is the distance between two Corresponding points on the wave and is measured in Metres.
   • Frequency (ƒ) - This is how many waves pass by every second and is measured in Hertz (Hz)
   • Time Period (T) - This is the time taken to produce one complete wave. T= 1/ƒ or ƒ=1/t

2. Types of Waves

   • Transverse Waves - When the displacement is at right angles to the direction of the wave.
   • Longitudinal Waves - When the displacement is parallel to the direction of the wave

3. The Wave Equation

   • Wave Speed (V) = Frequency (ƒ) x Wavelength (λ)

4. Electromagnetic Spectrum

   • Radiowaves
     • Microwaves
       • Infrared
         • Visible Light
           • Ultraviolet
             • X-rays
               • Gamma Rays
                 • Emitted from the nuclei of atoms,very penetrating and can be very harmful.
               • Can cause damage to body tissues, widely used in medicines. short wavelengths will pass body tissue.
             • Have shorter wavelength than visible light. The Sun is a natural source of ultraviolet light.
           • Yellow
           • Orange
           • Red
           • Green
           • Blue
           • Purple
           • commonly used to transmit signals by light and infrared radiation.
         • Absorbed energy of Infrared can generate Heat.
       • used in Mobile phones,Satellite TV
     • • Produced by High Frequency oscillations of electrons in aerial

5. Diffraction

   • Note: A Barrier on one side can also cause diffraction. Therefore Diffraction can cause a wave to pass around a bend.
   • More Diffraction if the size of the gap is similar to the wavelength
   • Is the spreading out of waves when they pass through a gap or round the edge of an obstacle.

6. LIGHT

   • Light is a transverse wave that travels in straight lines.
   • Angle of incidence = angle of reflection
   • Refractive index - There is a relationship between the incident angle and the refracted angle known as the REFRACTIVE INDEX. This is the ratio of the speed of light in air to the speed of light in the refracted material.
     • n= The Refractive index | i= angle of incidence in air | r= angle of Refraction in the other material
       • n= Sin 1 / Sin r

7. Sounds

   • Sounds are made when an object vibrates.
   • frequency range of the normal human ears is from about 20Hz to about 20000Hz
   • speed of sound is about 340 m/s
   • louder sounds have greater Amplitude whilst High Pitch Sounds have a shorter wavelength so more waves are visible, it has higher frequency waves.

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