Chapter 4.1

Properties of Waves

Waves transfer energy through matter or space.

Wave- disturbance that transfers energy through matter or space. Causes no permanent displacement.

Energy- application of force over distance.

Force- Push or pull on an object.

Wavelength- Distance from crest to crest, or trough to trough.

Crest- highest point of a wave.

Trough- lowest point of a wave.

Amplitude- height of a wave crest or depth of a trough, measured from its rest position.

Medium- Is the matter a wave travels through.

Transverse Wave- matter moves back and forth perpendicular

to direction the wave travels. (see figure 4.7)

1) Compression/Longitudinal

2) Transverse

Transverse Waves:

• Water and seismic (earthquake) waves are a combination of transverse

and compression waves.

• Visible light and radio waves travel through space. (no medium)

Compression/ Longitudinal Wave:

Matter moves back and forth along the same direction that the wave travels.

(see figure 4.8)

- Frequency = cycles/seconds

- Frequency is measured in “hertz” (hz). - Ex. The music express goes around 48 times in 12

seconds, what is its frequency?

- Frequency = cycles/ seconds

- F = 48/12

- F = 4 hz.

- Answer page 138 “what to do” #1) a – e. (answers on next slide)

1a) 4 hz

1b) 12 revolutions/ 120 s. = 0.1 Hz

1c) 30 flashes/ 30 s. = 1 Hz

1d) 18 beats/ 20 s. = 0.9 Hz

1e) 2000 revolutions/ 60 s. = 33.3 Hz

1) Find the following for

each example:

amplitude: -

frequency: -

wavelength: -

BC SCIENCE 8

Page 143: Questions #1 – 5 + 8 - 9.

• Visible light: is a mixture of all the colours of the rainbow.

•Different colours of light have different wavelengths.

•An object looks blue in sunlight because it reflects blue and

absorbs colours other than blue from the sunlight.

Visible Light:

Refraction: Is the bending or changing direction of a wave as

it passes from one material to another.

Reflection: Occurs when a light wave strikes

an object and bounces off.

The Visible Spectrum is known as: ROY G. BIV

Red Orange Yellow Green

Blue Indigo Violet

Think about the question and

exchange your thoughts with someone

beside you without leaving your seat.

Check your Understanding

Pg#151 #1- 9 + 12a

Gamma Ray burst from dying Star

Light Spreads out and radiates from the Sun and other stars in all directions.

Energy, such as light, that travels by radiation is often called radiant

energy. The Sun also radiates invisible energy. The light we see is just a

tiny band of a much broader spectrum of energy.

Electromagnetic radiation is the transmission of energy from

the longest radio waves to the shortest gamma rays.

Electromagnetic waves detected by our eyes are a small

portion of the entire spectrum. There are devices that can

detect other frequencies:

-Car Antenna: Detects Radio Waves

-X-Ray Machine: Detects X-Rays

-Infrared Goggles: Detects infrared Waves

Have the longest wavelength and lowest energy and

frequency compared to all other types. Radio, television, and

radar are examples of uses for radio waves.

Microwaves

Have the shortest wavelength and highest frequency of all

the radio waves. Only foods that contain water particles can

be heated using microwaves.

-Another example: telecommunications satellites.

Infrared waves have a longer wavelength and lower energy

and frequency compared to light.

Examples: Television remote controls and DVD players. Infrared radiation is used to

catch criminals at night etc.

Pg #157 #1-5

The Hubble Telescope takes such clear images

to send back to Earth because it orbits outside

the Earth’s atmosphere.

Ultraviolet Waves

Just beyond the violet end of the spectrum (ROY G BIV) are the ultraviolet (UV)

waves. These waves have a shorter wavelength and higher

energy and frequency than that of visible light.

Positive & Negative EX. Ultraviolet radiation allows your skin to make vitamin D for

healthy bones and teeth, too much UV can result in sunburns, skin cancers, and

damage to the surface of the eye.

The earth’s atmosphere absorbs

some of the UV radiation emitted by

the Sun.

The ozone layer

protects the earth

from harmful

radiation.

X RAYS:

X Rays have a much shorter wavelength and higher

energy and frequency than UV rays.

EX. X Rays are commonly used to photograph teeth and bones because they

can easily pass through tissues such as skin and muscle. Airports also use X

rays to scan luggage.

Gamma Rays (2 min 30 secs)

Gamma rays are the highest energy and frequency and

shortest wavelength of the electromagnetic spectrum.

Gamma rays result from nuclear reactions and are produced

from the hottest regions of the universe.

Pg 163: #1-6, 8-11.

Chapter 4 Review

Pg #164 & 165

#1- 3, 5 – 13, 15 +19.