The graph shows details about a wave - Edexcel - GCSE Physics - Question 1 - 2018 - Paper 1

To find the frequency of the wave, we can use the formula:

$f = \frac{v}{\lambda}$

where:

• $f$ is the frequency,
• $v$ is the speed of the wave (30 m/s), and
• $\lambda$ is the wavelength.

From the graph, we can observe that the distance between two consecutive peaks (the wavelength, $\lambda$) is 10 m. Substituting these values into the formula gives:

$f = \frac{30 \text{ m/s}}{10 \text{ m}} = 3 \text{ Hz}$

Answer: The frequency of the wave is 3 Hz.

The focal length of a lens is defined as the distance from the lens to the focal point, where parallel rays of light converge after passing through the lens. It is an important characteristic that determines the lens's ability to focus light and affects the magnification and clarity of the image formed by the lens.