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:

$$ \begin{aligned} T &= \frac{1}{f} \newline f &= \frac{1}{T} \end{aligned} $$

1. Give the name and unit for $T$ and $f$.
2. Red light has a frequency of $430THz$, what is its period?
3. Microwaves use a type of light with a period of approximately 4.0816327x10^{-10}s. What is its frequency?

Learning Outcomes ^🔗

1. Be able to use the frequency-period relationship.
2. 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.

1. What is the period of the waves?
2. What is the frequency of the waves?
3. A lifeguard measures the velocity of the waves to $300cms^{-1}$. What is their wavelength?

Whakatika ^🔗

1. What is the frequency of the waves?
   $f=\frac{1}{T}=\frac{1}{20}=0.05s^{-1}$
2. What is the period of the wave?
   $T=\frac{1}{f}=\frac{1}{0.05}=20s$
3. What is their wavelength?
   $v=f\lambda, \lambda=\frac{v}{f}=\frac{3}{0.05}=60m$

Ngohe / Task ^🔗

Worksheet!