Question

In your own words, explain the meaning of the following terms:

Transverse waves

Longitudinal waves

Standing waves

Shock waves

Answer 1

Transverse waves:-

Transverse waves are waves that are oscillating perpendicularly(at a right angle)to the direction of propagation. If you anchor one end of a ribbon or string and hold the other end in your hand, you can create transverse waves by moving your hand up and down. Notice though, that you can also launch waves by moving your hand side-to-side. This is an important point. There are two independent directions in which wave motion can occur. In this case, these motions are the Y and X directions mentioned above, while the wave propagates away in the z direction. The other type of waves is the longitudinal wave, which oscillates in the direction of its propagation.

A simple transverse wave can be represented by a sine or cosine curve, so called because the amplitude of any point on the curve its distance from the axis—is proportional to the sine (or cosine) of an angle. In the Figure, sine curves of various amplitudes are shown. These curves represent how a standing transverse wave might look at consecutive intervals of time. The time required for a point on the wave to make a complete oscillation through the axis is called the period of the wave motion, and the number of oscillations executed per second is called the frequency. Wavelength is considered to be the distance between corresponding points on the wave the distance between two adjacent peaks or troughs of the wave. Transverse waves may also be complex, in which the curves representing them are composed of two or more sine or cosine curves

Longitudinal waves:- If the particles of the medium vibrate in a direction parallel to the direction of propagation of the wave, it is called a longitudinal wave.

In longitudinal waves, the particle movement is parallel to the direction of wave propagation.

Longitudinal waves can travel through solids, liquids, and gases, as the medium requires only elasticity of volume for its propagation.

The longitudinal waves travel through a medium in the form of compressions and rarefactions. The region of high pressure is called compression and the region of low pressure is called rarefaction.

Sound waves and waves in a stretched spring are some examples of longitudinal waves.

Some waves are not purely transverse or longitudinal. For example, the seismic waves produced in the interior of earth travel both in the form of longitudinal and transverse waves.

Standing waves:- The modes of vibration associated with resonance in extended objects like strings and air columns have characteristic patterns called standing waves. These standing wave modes arise from the combination of reflection and interference such that the reflected waves interfere constructively with the incident waves. An important part of the condition for this constructive interference for stretched strings is the fact that the waves change phase upon reflection from a fixed end. Under these conditions, the medium appears to vibrate in segments or regions and the fact that these vibrations are made up of traveling waves is not apparent - hence the term "standing wave".

The behavior of the waves at the points of minimum and maximum vibrations contributes to the constructive interference which forms the resonant standing waves. The illustration above involves the transverse waves on a string, but standing waves also occur with the longitudinal waves in an air column. Standing waves in air columns also form nodes and antinodes, but the phase changes involved must be separately examined for the case of air columns.

Shock waves:- Shock wave, strong pressure wave in any elastic medium such as air, water, or a solid substance, produced by supersonic aircraft, explosions, lightning, or other phenomena that create violent changes in pressure. Shock waves differ from sound waves in that the wave front, in which compression takes place, is a region of sudden and violent change in stress, density, and temperature. Because of this, shock waves propagate in a manner different from that of ordinary acoustic waves. In particular, shock waves travel faster than sound, and their speed increases as the amplitude is raised; but the intensity of a shock wave also decreases faster than does that of a sound wave, because some of the energy of the shock wave is expended to heat the medium in which it travels. The amplitude of a strong shock wave, as created in air by an explosion, decreases almost as the inverse square of the distance until the wave has become so weak that it obeys the laws of acoustic waves. Shock waves alter the mechanical, electrical, and thermal properties of solids and, thus, can be used to study the equation of state of any material.