Amplitude Examples in Physics

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Amplitude.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Physics.

Concept Recap

The maximum displacement of a wave from its equilibrium (rest) position, measuring the wave's strength or intensity.

How 'tall' the wave is measured from the center line — bigger amplitude carries more energy and produces stronger effects.

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Amplitude relates to energy: energy \propto amplitude^2.

Common stuck point: Amplitude is measured from the middle (equilibrium), not from trough to peak.

Worked Examples

Example 1

easy
A speaker produces a sound wave. The air molecules vibrate 0.002 \text{ m} on either side of their equilibrium position. What is the amplitude of the sound wave?

Solution

  1. 1
    Amplitude is the maximum displacement from the equilibrium position.
  2. 2
    The molecules vibrate 0.002 \text{ m} from equilibrium, so the amplitude is A = 0.002 \text{ m}.
  3. 3
    The total peak-to-peak distance of vibration is 2A = 0.004 \text{ m}.

Answer

A = 0.002 \text{ m}
Amplitude is the maximum displacement of a point on a wave from its rest position. For sound waves, larger amplitude means louder sound. Amplitude is always measured from equilibrium, not peak-to-peak.

Example 2

medium
Two identical waves with amplitude A = 3 \text{ cm} overlap perfectly in phase. What is the resulting amplitude? What if they are perfectly out of phase (shifted by half a wavelength)?

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

medium
A wave on a string has amplitude 0.1 \text{ m} and frequency 2 \text{ Hz}. The string has a linear mass density of 0.05 \text{ kg/m} and the wave speed is 10 \text{ m/s}. What is the power transmitted by the wave? Use P = \frac{1}{2}\mu\omega^2 A^2 v.

Example 2

hard
A seismograph records an earthquake wave with amplitude 2 \text{ mm}. A second earthquake produces waves with 4 times the energy. What is the amplitude of the second earthquake's waves?
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Related Concepts

WavesEnergy

Background Knowledge

These ideas may be useful before you work through the harder examples.

waves