Edexcel A Level Physics:复习笔记5.2 The Wave Equation

The Wave Equation

• This equation links wave speed, frequency and wavelength

• Where:
  • v = velocity of the wave (m s–1)
  • f = frequency of the wave (Hz)
  • λ = wavelength (m)

   

• The wave equation tells us that for a wave of constant speed:
  • As the wavelength increases, the frequency decreases
  • As the wavelength decreases, the frequency increases

   

The relationship between frequency and wavelength of a wave

Step 1: Write down the known quantities

• • Period, T = 1.0 μs = 1.0 × 10–6 s
  • Velocity, c = 100 cm s–1 = 1.0 m s–1

   

Note the conversions:

• • The period must be converted from microseconds (μs) into seconds (s)
  • The velocity must be converted from cm s–1 into m s–1

   

Step 2: Write down the relationship between the frequency f and the period T

Step 3: Substitute the value of the period into the above equation to calculate the frequency

f = 1.0 × 106 Hz

Step 4: Write down the wave equation

c = fλ

Step 5: Rearrange the wave equation to calculate the wavelength λ

Step 6: Substitute the numbers into the above equation

λ = 1 × 10–6 m