# Physics Lesson 11.7.2 - Huygens Principle

Please provide a rating, it takes seconds and helps us to keep this resource free for all to use

Welcome to our Physics lesson on Huygens Principle, this is the second lesson of our suite of physics lessons covering the topic of Diffraction of Waves, you can find links to the other lessons within this tutorial and access additional physics learning resources below this lesson.

## Huygens Principle

The Dutch scientist Christiaan Huygens developed a useful technique for determining in detail how and where waves propagate during diffraction. Starting from some known position, Huygens's principle states that every point on a wave front is a source of wavelets that spread out in the forward direction at the same speed as the wave itself. The new wave front is tangent to all of the wavelets.

We saw the application of Huygens Principle in all examples discussed so far. For example, if a door is 73.5 cm wide and a 1400 Hz sound wave moving at 343 m/s passes through it, there are three simultaneous wavefronts produced, as

λ = v/f
= 343 m/s/1400 Hz
= 0.245 m
= 24.5 cm

Therefore, since the width of the door is d = 73.5 cm, the number of waves that can pass simultaneously through the door is

N = d/λ
= 73.5 cm/24.5 cm
= 3

Look at the figure below:

We will discuss more extensively Huygens Principle and diffraction in general in our Physics tutorial on "Interference and Diffraction of Light", where more numerical examples and techniques will be explained.

You have reached the end of Physics lesson 11.7.2 Huygens Principle. There are 2 lessons in this physics tutorial covering Diffraction of Waves, you can access all the lessons from this tutorial below.

## More Diffraction of Waves Lessons and Learning Resources

Waves Learning Material
Tutorial IDPhysics Tutorial TitleTutorialVideo
Tutorial
Revision
Notes
Revision
Questions
11.7Diffraction of Waves
Lesson IDPhysics Lesson TitleLessonVideo
Lesson
11.7.1What is Diffraction?
11.7.2Huygens Principle

## Whats next?

Enjoy the "Huygens Principle" physics lesson? People who liked the "Diffraction of Waves lesson found the following resources useful:

1. Huygens Principle Feedback. Helps other - Leave a rating for this huygens principle (see below)
2. Waves Physics tutorial: Diffraction of Waves. Read the Diffraction of Waves physics tutorial and build your physics knowledge of Waves
3. Waves Revision Notes: Diffraction of Waves. Print the notes so you can revise the key points covered in the physics tutorial for Diffraction of Waves
4. Waves Practice Questions: Diffraction of Waves. Test and improve your knowledge of Diffraction of Waves with example questins and answers
5. Check your calculations for Waves questions with our excellent Waves calculators which contain full equations and calculations clearly displayed line by line. See the Waves Calculators by iCalculator™ below.
6. Continuing learning waves - read our next physics tutorial: Types of Waves. The Simplified Equation of Waves

## Help others Learning Physics just like you

Please provide a rating, it takes seconds and helps us to keep this resource free for all to use