Key Stage 3
Meaning
Wave Speed is how quickly a wave travels through a medium.
About Wave Speed
- Wave Speed is measured in metres per second.
- The wave speed states how quickly energy and information can be transferred by a wave.
Equation
Equation 1
\(v = \frac{x}{t}\)
Where:
v = Wave Speed
x = distance traveled
t = time taken to travel
Equation 2
\(v = f \lambda\)
\(v = f \times \lambda\)
Where:
v = Wave Speed
λ = wavelength of the wave
Key Stage 4
Meaning
Wave Speed is how quickly a wave travels through a medium.
About Wave Speed
- Wave speed is a scalar because it has magnitude only.
- The SI Unit of wave speed is metres per second.
- The wave speed states how quickly energy and information can be transferred by a wave.
Equation
Equation 1
\[v = \frac{x}{t}\]
Where:
v = Wave Speed
x = distance traveled
t = time taken to travel
Equation 2
\(v = f \lambda\)
Where:
v = Wave Speed
λ = wavelength of the wave
Example Calculations
Finding Wave Speed from Wavelength and Frequency
| A water wave has a wavelength of 1.6m and a frequency of 1.5Hz. Calculate the speed of the wave. | A ray of ultravoilet light with a frequency of 7.5x1014Hz and wavelength of 0.30μm in an optical fibre. Calculate the speed of the wave through that optical fibre correct to 2 significant figures. |
| 1. State the known quantities
f = 1.5Hz λ = 1.6m |
1. State the known quantities
f = 7.5x1014Hz λ = 0.30μm = 0.30x10-6m |
| 2. Substitute the numbers into the equation and solve.
\(v = f \lambda\) \(v = 1.5 \times 1.6\) \(v = 2.4m/s\) |
2. Substitute the numbers into the equation and solve.
\(v = f \lambda\) \(v = 7.5 \times 10^14 \times 0.30 \times 10^{-6}\) \(v = 225000000m/s\) \(v \approx 2.3 \times 10^8 m/s\) |
Finding Wave Speed from Distance Travelled and Time Taken
| A scientist observes a wave in a ripple tank. The length of the tank is 0.75m and it takes the wave 1.2 seconds to get from one end of the tank to the other. Calculate the wave speed of the wave correct to two significant figures. | Question |
| 1. State the known quantities | 1. State the known quantities |
| 2. Substitute the numbers into the equation and solve. | 2. Substitute the numbers into the equation and solve. |