Waves - Revision

Waves transfer from one place to another. Oscillations in a longitudinal wave are to the direction of energy transfer. Oscillations in a transverse wave are to the direction of energy transfer. Sound waves are , electromagnetic waves are and mechanical waves (e.g. on a slinkly spring) can be either or .

The number of waves that pass in one second is called the wave , measured in (). The amplitude of a wave goes from the to the , while the wavelength goes from to .

Light of a single frequency is described as .

The speed of a wave can be found using the equation: = x

v = (units: )
f = (units: )
λ = (units: )

A radio station transmits radio waves at a frequency of 2 x 10^5 Hz. The speed of radio waves is 3.0 x 10^8 m/s. Calculate the wavelength of the radio waves.

To answer the question, you must use the formula = x .
The answer to the question is:

The electromagnetic spectrum is a family of waves which can all:
1) Travel at the speed of (about )
2) Travel through a (empty space - no medium required!)
3) Transfer from one place to another.

The higher the frequency (the the wavelength) of electromagnetic radiation, the more it transfers.
This is why rays (from radioactive material), x-rays (used in ), and radiation (from the sun) can be harmful to living tissue.

State the safety issues regarding the use of microwaves and x-rays:
Microwaves: can up body , damage
X-Rays: can cause , kill , cause changes

radiation and waves are able to penetrate your skin. Their energy can be by body tissue, which can internal organs and may damage them. radiation from the sun is absorbed by your . Too much of this can cause .

Describe the uses of these electromagnetic waves:
Radio Waves: r
Microwaves: s , m , h
Infra-red: r , i , o , r
X-Rays: m, a

If a wave source (such as from a distant galaxy, or from a passing ambulance) moves away from an observer, the observed wavelength and the frequency . This is known as the effect.

If the wave source moves towards the observer, the complete happens. The wavelength , while the frequency .

Name four types of mechanical waves:
w
on a s
s
e

w are t
on a s can be l or t
s are l
e can be l (p wave) or t (e wave)

Sound is caused by which make pressure waves move through a substance (such as air).

In a sound wave, particles oscillate to the direction of the wave motion.

A sound wave is therefore a type of wave.

The hearing frequency of an average human is Hz - .

In a sound wave:
Pitch depends on the wave's .
Loudness depends on the wave's .
Echoes are caused when the wave off an object.

Sound waves need a (a material) to travel through (they cannot travel through a ).

Describe a simple experiment to determine the speed of sound in air:
• Stand 100m away from a brick
• your hands
• Use a to measure the time taken between you clapping your hands and the returning to you
• the experiment at least times
• Use the formula = / to calculate the

What are some typical values of the speed of sound in:
Gases: m/s
Liquids: m/s
Solids: m/s