Mobile: 0716 858334 / 0712 054195
Change Class  |  Change Subject

Waves I - Form Two Physics

Waves I

  Change Class FORM TWO
Select Subject  |  Physics

Guest Account

Hello Guest, Create an Account or Login to save your progress and get unlimited access to more notes, revision exercises and answers.

Feeling Ready?

Attempt Form Two Physics Questions
Guest Account
Hello Guest, Create an Account or Login to save your progress and get unlimited access to more notes, revision exercises and answers.

Waves I

- A wave is simply a disturbance that moves through a medium. Other waves do not require a medium to travel i.e. they can travel in a vacuum, are known as electromagnetic waves e.g. radio, X-rays, gamma rays UV rays etc.
- Other waves require a material medium to be transferred and are called mechanical waves i.e. water, sound waves etc.

Transverse and longitudinal pulses and waves

1. Transverse waves

– They consist of a crest and a trough.
- In this case the displacement of the medium caused by these pulses are perpendicular to the direction in which the wave (disturbance) travels.
- A pulse is a single non-repeated disturbance.
- If the pulses are repeated periodically (regularly) they produce a series of waves called periodic transverse wave train.
- They can be produced as shown below.

Furniture From Wood - Geography Form Two

2. Longitudinal waves

- These are waves whereby the particles of the medium vibrate parallel to the direction of movement of the disturbance.
- When several turns of a spring are pulled together (compression) and then released they tend to spread out to their original position.
- When pulled apart (rarefaction) they also turn to their original position.
- In this case the displacement of the spring is parallel to the motion of the wave and this is known as longitudinal.

Furniture From Wood - Geography Form Two

Characteristics of waves

  1. All waves have speed which depends on the nature of disturbance.
  2. All waves have wavelength (distance between two successive points in a wave). Represented by the symbol λ and is measured in metres.
  3. All waves have frequency - ' f ' which is the number of waves passing a point in one second. It is measured in cycles per second or hertz (Hz). The period of a wave is the time required for a complete wave to pass a given point.
    Therefore T = 1 / f or f = 1 / T (period is measured in seconds).
    The speed 'v' is given as: v = λ / T, since f = 1 / T then v = (1 / T) x λ = f λ or v = f λ. This is the wave equation.
  4. All waves have amplitude which is the maximum displacement of the particles of the medium as the wave passes.
Example 1
1. A rope is displaced at a frequency of 3 Hz. If the distance between two successive crests of the wave train is 0.8 m, calculate the speed of the waves along the rope.
Solution
v = f λ = 3 x 0.8 = 2.4 m
Hz = 2.4 m/s.

Example 2
2. The figure below illustrates part of the displacement-time graph of a wave travelling across water at a particular place with a velocity of 2 ms-1 Calculate the wave's:
a) Amplitude
b) Frequency (f)
c) Wavelength (λ)

Furniture From Wood - Geography Form Two

Solution
a) From the graph, maximum displacement
(a) = 0.4 cm.
b) From the graph, period T = time for one cycle = 0.20 seconds.
So f = 1 / T = 1 / 0.20 = 5 Hz.
c) Velocity = f λ hence λ = 2 / 5 = 0.4 m.

Hello Guest, Please help review these notes.    Why review

Your review has been successfully submitted.
Tell us what you think about the notes.

Submit Comment