Transverse and longitudinal waves (copy)

6.01

Waves can be drawn as wavefronts. What is a wavefront?

A wavefront can be thought of the peak of a transverse wave or the compression of a longitudinal wave.

What are oscillations?

to-and-fro movements

What are transverse waves?

When the oscillations are up and down or from side to side. In transverse waves, the oscillations are at right-angles to the direction of travel. Light waves are transverse waves, although it is electrical and magnetic fields which oscillate, rather than any material.

Example of transverse waves:

Electromagnetic waves:

• radio waves

• microwaves

• infrared rays

• light

• ultraviolet rays

• X-rays

• gamma rays

What are longitudinal waves?

When the oscillations are backwards-and-forwards, and the oscillations are in the directions of travel.

There are sections of compression and of rarefaction.

* When we speak - compressions and rarefactions travel through the air.

Examples of longitudinal waves:

Sound waves

• guitar string

• When we speak - compressions and rarefactions travel through the air.

What is the speed of waves measured in?

The speed of the waves is measured in metres per second (m/s)

What is the frequency of waves?

And what is the SI unit?

This is the number of waves passing any point per second. The SI unit of frequency is hertz (Hz).

What is the time for one oscillation called?

And what is it equal to?

A period.

It is equal to 1/frequency.

What is a period?

Period (in seconds) is the time for one oscillation.

Frequency = 1/period

A wave makes 4 oscillations per second. What is the frequency? And what is the period

A wave makes 4 oscillations per second, then 4 waves pass any point per second, and the frequency is 4 Hz. If the frequency is 4 Hz, the period is 1/4 s (0.25 s)

What is a wavelength?

The distance between any point on a wave and the equivalent point on the next.

What is amplitude?

This is the maximum distance a point moves from its rest position when a wave passes.

What is the wave equation?

Speed = frequency x wavelength