Period, Frequency and Wavelength
12PHYS - Wave Systems
Finn Le Sueur
2024
Mahi Tuatahi
The period is very closely linked to the frequency as you can see
from their definitions. There is a very simple formula for converting
between them:
\[
\begin{aligned}
T &= \frac{1}{f} \newline
f &= \frac{1}{T}
\end{aligned}
\]
- Give the name and unit for \(T\) and \(f\).
- Red light has a frequency of \(430THz\), what is its period?
- Microwaves use a type of light with a period of
approximately 4.0816327x10^{-10}s. What is its frequency?
Learning Outcomes
- Be able to use the frequency-period
relationship.
- Be able to use the wave equation.
The Wave Equation
We can also relate the velocity,
frequency, and wavelength with the
wave equation:
\[
\begin{aligned}
v &= f\lambda
\end{aligned}
\]
Label each part of this equation with its name and unit.
Pātai
Mathieu is surfing at Taylors Mistake and decides to count the waves.
He notices that 3 waves pass him over 60s.
- What is the period of the waves?
- What is the frequency of the waves?
- A lifeguard measures the velocity of the waves to
\(300cms^{-1}\). What is their
wavelength?
Whakatika
- What is the frequency of the waves?
\(f=\frac{1}{T}=\frac{1}{20}=0.05s^{-1}\)
- What is the period of the wave?
\(T=\frac{1}{f}=\frac{1}{0.05}=20s\)
- What is their wavelength?
\(v=f\lambda,
\lambda=\frac{v}{f}=\frac{3}{0.05}=60m\)