Wave Motion

A wave carries energy and a pattern through space or a medium. The material in the medium may oscillate around equilibrium without traveling along with the wave.

This lesson supports Chapter 14 of Physics for Beginners. Keep the physical picture in view, write the units, and check the direction of every vector before trusting a calculation.

Amplitude, wavelength, and frequency measure different features

Amplitude is the maximum displacement from equilibrium. Wavelength \(\lambda\) is the distance between matching points on neighboring cycles. Frequency \(f\) counts cycles per second. Period and frequency satisfy \(T=1/f\).

Wave speed connects space and time

The basic wave relation is \[v=f\lambda.\] In a fixed medium, wave speed is set mainly by the medium. If frequency rises while speed stays constant, wavelength must decrease. A source controls frequency, but a new medium can change speed and wavelength.

Transverse and longitudinal waves move differently

In a transverse wave, the disturbance is perpendicular to the direction of travel. In a longitudinal wave, the disturbance is parallel, producing compressions and rarefactions. Reflections can combine into standing waves with nodes and antinodes.

Worked example

A wave has frequency \(5\text{ Hz}\) and wavelength \(2.4\text{ m}\). Its speed is \(v=f\lambda=5(2.4)=12\text{ m/s}\).

Watch the idea in action

FuseSchool – Global Education gives a focused explanation of the chapter’s central idea. Pause before each calculation and predict the next step on paper.

Practice questions

1. What does wave amplitude measure?
2. What is wavelength?
3. Write the wave-speed equation.
4. How are frequency and period related?
5. In a transverse wave, which way does the medium move?
6. What is a node in a standing wave?

Answers

1. Maximum displacement from equilibrium.
2. The distance between matching points on neighboring cycles.
3. \(v=f\lambda\).
4. \(T=1/f\).
5. Perpendicular to the wave’s travel direction.
6. A point of zero displacement.

Keep studying

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