Huygen's principle states that each point on a wavefront can be considered a secondary wave source that propagates spherical wavelets. When these wavelets meet, they can constructively or destructively interfere to form a new wavefront. The document explains how Huygen's principle can be applied to understand how sound waves propagate around barriers and how it relates to the double slit experiment and the observed interference pattern.

1. Huygen’s Principle

2. Huygen’s Principal
• Hugyen’s principal states that each point along a wave can be the
source for subsequent spherical waves.
Planar wave front Planar wave front
with evenly spaced
points
Planar wave front
with spherical waves
projecting from points
New wave front is
drawn tangent to
circles

3. Barrier
Barrier
Barrier
Wave front approaches
a barrier
Choose a point on the
wave to apply Huygen’s
principle
That point is the source
of new, circular waves
Because of this
propagation someone
standing here could still
hear the sound, despite
being behind the barrier.
Application of Huygen’s principle to sound waves

4. A wave
approaches a
barrier with
two slits and
new waves
propagate from
the points at
the slits.
Huygen’s principle and the double slit experiment
Using Huygen’s
principle to visualize
the new waves it is
easy to see the where
the waves
constructively
interfere. This explains
the pattern of
constructive and
destructive
interference observed
in the double slit
experiment.