WARM UPWARM UP

ON YOUR INDEX CARD, WRITE ONE SENTENCE ABOUT THE RELATIONSHIP BETWEEN ELECTRICITY AND MAGNETISM!

Light and SoundLight and Sound

In this SECTION:

1) What is light?2) Electromagnetic Spectrum3) Interactions of Light4) Color

What is light?What is light?

Light is an electromagnetic wave!

An electromagnetic wave is a wave that travels through empty space or matter and consists of changing electric and magnetic fields!

How are EM Waves How are EM Waves ProducedProduced

An EM wave can be produced by the vibration of an electrically charged particle. When the particle vibrates, the electric field around it also vibrates. When the electric field vibrates, it creates a vibrating magnetic field. The vibration of both fields together produces an EM wave. The transfer of energy as electromagnetic waves is called RADIATION!

Properties of LightProperties of Light

Light travels in straight lines:

Laser

Light travels VERY FAST – around 300,000 km/sec. This is 880,000

times faster than sound.

At this speed it can go around the world 8 times in one second.

Light travels fastest through empty space!

Light travels much faster than sound. For example:

1) Thunder and lightning start at the same time, but we will see the lightning first.

2) When a starting pistol is fired we see the smoke first and then hear the bang.

Shadows

Shadows are places where light is “blocked”:

Rays of light

Properties of Light Properties of Light summarysummary

1) Light travels in straight lines2) Light travels much faster than sound3) Shadows are formed when light is

blocked by an object

2. The Electromagnetic 2. The Electromagnetic SpectrumSpectrum

Entire range of EM waves!

Divided into regions according to wavelength

Where is the highest energy?

EM SPECTRUMEM SPECTRUM

Description

1. Used by police officers to detect the speed of cars by radar2. Energy from the sun that cancause sunburn3. Used in a device that takes images of bones4. Carry television signals to yourhome5. Can produce rainbows when there are water droplets in the sky6. Used to treat forms of cancer or sterilize food

Region of EM spectrum

1. MICROWAVES/RADAR

2. ULTRAVIOLET

3. X-RAYS

4. RADIO

5. VISIBLE LIGHT

6. GAMMA RAYS

VISIBLE LIGHT:NARROW RANGE VISIBLE LIGHT:NARROW RANGE OF WAVELENGTHSOF WAVELENGTHS

LONGEST TO SHORTEST

WAVELENGTH

RedOrangeYellowGreenBlue

IndigoViolet

3. INTERACTIONS OF LIGHT3. INTERACTIONS OF LIGHT

REFLECTION/LAW OF RELFECTIONTYPES OF REFLECTION

LIGHT SOURCE V. REFLECTED LIGHTABSORPTIONSCATTERINGREFRACTIONDIFFRACTION

We see things because they reflect light into our eyes:

Homework

ReflectionReflectionReflection from a mirror:

Incident ray

Normal

Reflected ray

Angle of incidence

Angle of reflection

Mirror

The Law of ReflectionThe Law of Reflection

Angle of incidence = Angle of Angle of incidence = Angle of reflectionreflection

In other words, light gets reflected from a surface at ____ _____ angle it hits it.

The same !

!!

Clear vs. Diffuse ReflectionClear vs. Diffuse Reflection

Smooth, shiny surfaces have a clear reflection:

Rough, dull surfaces have a diffuse reflection.

Diffuse reflection is when light is scattered in different directions

Luminous and non-luminous objects

A luminous object is one that produces light.

An illuminated object is one that reflects light.

Luminous objects Illuminated

FIREFLY

SUN

LIGHT BULB

A VISIBLE OBJECT THAT IS NOT A LIGHT SOURCE

ABSORPTIONABSORPTION

THE ABSORPTION OF LIGHT ENERGY BY MATTER-CAUSES LIGHT TO BECOME

DIMMER. THE FARTHER LIGHT TRAVELS FROM THE SOURCE, THE DIMMER IT

BECOMES

SCATTERING SCATTERING

INTERACTION THAT CAUSES LIGHT TO CHANGE DIRECTION

ALLOWS YOU TO SEE OBJECTS OUTSIDE THE BEAM, BUT BECAUSE LIGHT IS SCATTERED, BEAM BECOMES DIMMER.

RefractionRefraction

Refraction is when waves ____ __ or slow down due to travelling in a different _________. When a pen is placed in water it looks like this:

In this case the light rays are slowed down by the water and are _____, causing the pen to look odd. The two mediums in this example are ______ and _______.

Words – speed up, water, air, bent, bend. medium

REFRACTION AND COLOR REFRACTION AND COLOR SEPARATIONSEPARATION

RedOrangeYellowGreenBlue

IndigoViolet

Violet light, which has a shorter wavelength, is refracted more than red light

DIFFRACTIONDIFFRACTION

LIGHT CANNOT BEND VERY MUCH BY DIFFRACTION UNLESS IT PASSES THROUGH A VERY NARROW OPENING OR AROUND A SMALL BARRIER.

LIGHT CANNOT DIFFRACT VERY MUCH AROUND LARGE OBJECTS

TRANSMISSIONTRANSMISSION

LIGHT PASSES THROUGH MATTTER.

ALL OF THE LIGHT THAT REACHES YOUR EYES IS TRANSMITTED

THROUGH AIR.

3. Colour3. Colour

White light is not a single colour; it is made up of a mixture of the seven colours of the rainbow.

We can demonstrate this by splitting white light with a prism:

This is how rainbows are formed: sunlight is “split up” by raindrops.

TYPES OF MATTERTYPES OF MATTER

1. TRANSPARENT-LIGHT IS TRANSMITTED THROUGH EASILY

2. TRANSLUCENT-TRANSMITS AND SCATTERS

3. OPAQUE- DOES NOT TRANSMIT LIGHT

How is color determined?How is color determined?The colour an opaque object appears depends on

the colours of light it reflects.

For example, the book only reflects red light so we see it as red!

White

light

Only red light is

reflected

A white hat would reflect all seven colours:

A pair of purple trousers would reflect purple light (and red and blue, as purple is made up of red and

blue):

Purple light

White

light

Using coloured lightUsing coloured light

If we look at a coloured object in coloured light we see something different. For example, consider a football kit:

White

light

Shorts look blue

Shirt looks red

In different colours of light this kit would look different:

Red

lightShirt looks red

Shorts look black

Blue

light

Shirt looks black

Shorts look blue

The white hair reflects all the light….the black hair absorbs all the light

Colors of Transparent and Colors of Transparent and Translucent ObjectsTranslucent Objects

The color of transparent and translucent objects is determined differently.

Color is determined by what is transmitted.

Glass is clear because it transmits all light. Ginger ale 2-Liters are green because the plastic transmits green light

Mixing coloursMixing coloursWhite light can be split up to make separate

colours. These colours can be added together again.

The primary colours of light are red, blue and green. Combining colors of light is called color addition

Adding blue and red makes magenta (purple)

Adding blue and green makes cyan

(light blue)

Adding all three makes white again

Adding red and green makes yellow

TV SETSTV SETS

USE RED, BLUE AND GREEN PLATES TO

MAKE ALL THE COLOR YOU SEE!

PIGMENTSPIGMENTS

A PIGMENT is a material that gives a substance its color by absorbing some colors of light and reflecting others.

Chlorophyll is a pigment as is melanin (skin pigment) and paint colors

MIXING PIGMENTSMIXING PIGMENTS

WHEN YOU MIX PIGMENTS TOGETHER, MORE COLORS OF LIGHT ARE ABSORBED OR TAKEN AWAY.

MIXING PIGMENTS IS CALLED COLOR SUBTRACTION

Sound – The basicsSound – The basics

We hear things when they vibrate.

If something vibrates with a high frequency (vibrates very ______) we say it has a _____ pitch.

If something vibrates with a low frequency (vibrates ______) we say it has a ____ pitch.

The lowest frequency I could hear was…

Words – slowly, low, high, quickly

Drawing sounds…Drawing sounds…

This sound wave has a _____ frequency:

This sound wave has a ___ _frequency:

Drawing sounds…Drawing sounds…

This sound wave has a _____ amplitude (loud):

This sound wave has a _____ amplitude (quiet):

Hearing problemsHearing problems

Our hearing range can be damaged by several things:

1) Too much ear wax!

2) Damage to the auditory nerve

3) Illness or infections

4) Old age (not like Mr Richards)

Other sound effects…Other sound effects…

Like light, sound can be…

1) Reflected – sound reflections are called ______.

2) Refracted – this is why you might sound strange if you try talking underwater

The EarThe Ear

Label your diagram with the following:

These bones are vibrated by the eardrum

This tube carries the sound towards the eardrum

This part is used to help us keep our balance

This part “picks up” the vibrations

This part of the ear contains many small hairs with turn vibrations into an electrical signal

This part connects the ear to the mouth

This part “channels” the sound towards the ear drum

The EarThe Ear