A wave is an energy transfer through a medium without the medium itself moving very far from its equilibrium position. For instance, think about a wave in the ocean; it moves forward even though the water particles stay in place.
The speed of a wave (v) is determined by its wavelength (λ) and period (T). The formula for wave speed is given by
v = \(\frac λT\)
But, we know that the frequency of a wave (f) is the inverse of its period
f = \(\frac 1T\)
So, we can also write the wave equation as
v = fλ
Example 1: String wave
If you're moving a stretched string up and down at a regular interval, you create a wave. For example, if the wavelength is 1.1m and you move it every 0.60s (period), you can calculate the wave's speed
v = \(\frac λT\) = 0.601.1 = 1.8ms−1
Example 2: Lake wave
Imagine you're observing a wave on a lake. You notice the wave has moved 0.60m in 0.25s and has a wavelength of 2.8m. You can calculate its speed
v = \(\frac {0.60}{0.25}\) = 2.4ms−1
And its period
T = \(\frac λv\) = \(\frac {2.8}{2.4}\) = 1.2s
Dive deeper and gain exclusive access to premium files of Physics HL. Subscribe now and get closer to that 45 🌟
A wave is an energy transfer through a medium without the medium itself moving very far from its equilibrium position. For instance, think about a wave in the ocean; it moves forward even though the water particles stay in place.
The speed of a wave (v) is determined by its wavelength (λ) and period (T). The formula for wave speed is given by
v = \(\frac λT\)
But, we know that the frequency of a wave (f) is the inverse of its period
f = \(\frac 1T\)
So, we can also write the wave equation as
v = fλ
Example 1: String wave
If you're moving a stretched string up and down at a regular interval, you create a wave. For example, if the wavelength is 1.1m and you move it every 0.60s (period), you can calculate the wave's speed
v = \(\frac λT\) = 0.601.1 = 1.8ms−1
Example 2: Lake wave
Imagine you're observing a wave on a lake. You notice the wave has moved 0.60m in 0.25s and has a wavelength of 2.8m. You can calculate its speed
v = \(\frac {0.60}{0.25}\) = 2.4ms−1
And its period
T = \(\frac λv\) = \(\frac {2.8}{2.4}\) = 1.2s
Dive deeper and gain exclusive access to premium files of Physics HL. Subscribe now and get closer to that 45 🌟
AI Assist
Expand