Chapter 14.1 Notes

Condensed Waves Notes:

Wave – an oscillating disturbance that travels through a medium from one location to another location

Properties of Waves:
Amplitude (A) – maximum amount of displacement from the rest position
Units: m

Wavelength (l) - the length of one complete wave cycle
Units: m (nm is used for light!)

Frequency (f) – the number of complete vibrational cycles of a medium per a given amount of time
Units: Hz = 1/s

Period (T) – the time it takes to make one vibrational cycle (one wavelength)
Units: s

Speed (v) = the distance traveled by a given point on the wave in a given interval of time
v=l*f =l/T
Units: m/s

Transverse vs. Longitudinal Waves
Transverse: a wave in which the particles of the medium are displaced in a direction perpendicular to the direction of energy transport
Longitudinal: a wave in which the particles of the medium are displaced in a direction parallel to the direction of energy


Section 1: Types of Waves

Waves can be thought of as travelling energy. Waves are produced by some kind of oscillator. If there is only one cycle of vibration from the oscillator, a single pulse of energy will be produced that radiates away from the oscillator. If the oscillator repeats the vibration, a wave train will be produced.

There are two principle types of waves for us to examine at this point: Mechanical and Electromagnetic.




Wave characteristics:

If waves are produced by an oscillator that repeats it's cycle regularly, then a series of pulses called a wave train results.

The speed at which a mechanical wave passes through a given medium is generally fixed for any given set of conditions.

Check it out:

So.. to arrive at wavelength, we multiplied speed times period:

But period and frequency are inverses of each other, so we could just as well write this formula as

If you solve this equation for velocity, you arrive at the basic wave formula:


The amount, or distance from some resting point, that a wave displaces the medium it is travelling through is called the amplitude of the wave.

This diagram illustrates the features of a sine wave, but the same features can be identified on any type of mechanical wave.

Homework: set #1, Ch 14 Questions 1-10 Set#1 Ch 14 probs 32-40

Demonstrations: Mechanical waves on a long spring.