CSET Practice Test on Waves

In a longitudinal wave the particle displacement is
parallel to the direction of wave propagation. The
particles do not move down the tube with the wave; they
simply oscillate back and forth about their individual
equilibrium positions. Pick a single particle and watch
its motion. The wave is seen as the motion of the
compressed region (ie, it is a pressure wave), which moves
from left to right.

In a longitudinal wave, particles of the medium are
displaced in a direction parallel to energy transport. The
result is that energy is transported from one end of the
medium to the other end of the medium without the actual
tranport of matter. In this type of wave - a longitudinal
wave - the particles of the medium move in a direction
parallel to the direction of energy transport. 

A sound wave is a classic example of a longitudinal wave.
As a sound wave moves from the lips of a speaker to the
ear of a listener, particles of air vibrate back and forth
in the same direction and the opposite direction of energy
transport. Each individual particle pushes on its
neighboring particle so as to push it forward. The
collision of particle #1 with its neighbor serves to
restore particle #1 to ints original position and displace
particle #2 in a forwards direction. This back and forth
motion of particles in the direction of energy transport
creates regions within the medium where the particles are
pressed together and other regions where the particles are
spread apart. Longitudinal waves can always be quickly
identified by the presence of such regions. This process
continues along the chain of particles until the sound
wave reaches the ear of the listener.

Waves traveling through a solid medium can be either
transverse waves or longitudinal waves. Yet waves
traveling through the bulk of a fluid (such as a liquid or
a gas) are always longitudinal waves. Transverse waves
require a relatively rigid medium in order to transmit
their energy. As one particle begins to move it must be
able to exert a pull on its nearest neighbor. If the
medium is not rigid as is the case with fluids, the
particles will slide past each other. This sliding action
which is characteristic of liquids and gases prevents one
particle from displacing its neighbor in a direction
perpendicular to the energy transport. It is for this
reason that only longitudinal waves are observed moving
through the bulk of liquids such as our oceans.
Earthquakes are capable of producing both transverse and
longitudinal waves which travel through the solid
structures of the Earth. When seismologists began to study
earthquake waves they noticed that only longitudinal waves
were capable of traveling through the core of the Earth.
For this reason, geologists believe that the Earth's core
consists of a liquid - most likely molten iron.

In a transverse wave the particle displacement is
perpendicular to the direction of wave propagation. The
particles do not move along with the wave; they simply
oscillate up and down about their individual equilibrium
positions as the wave passes by. Pick a single particle
and watch its motion.

Radio waves, light waves, and heat waves are examples of
transverse waves. 

Waves traveling through a solid medium can be either
transverse waves or longitudinal waves. Yet waves
traveling through the bulk of a fluid (such as a liquid or
a gas) are always longitudinal waves. Transverse waves
require a relatively rigid medium in order to transmit
their energy. As one particle begins to move it must be
able to exert a pull on its nearest neighbor. If the
medium is not rigid as is the case with fluids, the
particles will slide past each other. This sliding action
which is characteristic of liquids and gases prevents one
particle from displacing its neighbor in a direction
perpendicular to the energy transport. It is for this
reason that only longitudinal waves are observed moving
through the bulk of liquids such as our oceans.
Earthquakes are capable of producing both transverse and
longitudinal waves which travel through the solid
structures of the Earth. When seismologists began to study
earthquake waves they noticed that only longitudinal waves
were capable of traveling through the core of the Earth.
For this reason, geologists believe that the Earth's core
consists of a liquid - most likely molten iron.