Science

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CHAPTER 9

CH 9.1

Definitions:

Wave: transmitter of energy without

the movement of particles from place to place. The vibration of particles of

energy fields is involved.

Transverse Waves: wave involving the

vibration of particles perpendicular to the direction of energy transfer.

Medium: material through which a wave

moves.

Vibrations: repeated fast

back-and-forth movements.

Compression: region in which the

particles are closer than when not disturbed by a wave.

Rarefaction: region in which the

particles are farther apart than when not disturbed by a wave.

Frequency: number of vibrations in

one second.

Hertz: unit of frequency: one hertz

is equal to one vibration per second.

Pitch: highness and lowness of a

sound.

Wavelengths: distance between two

neighbouring crests or troughs of a wave.

Notes:

Two types of waves:

Waves on water are called transverse waves. The moving particles in a

transverse wave travel at right angles to the direction of the energy transfer.

In a compression wave, the moving particles move backwards and forwards in the

same direction as the energy transfer.

Sound Waves:

sound is a compression wave. All sounds are caused by vibrations.

CH 9.2

Definitions

Sonar: use of reflected sound waves

to locate objects under water (sound navigation and ranging)

Echolocation: use of sound to locate

objects by deleting echoes.

Ultrasound: sound with frequencies

too high for humans to hear.

Notes:

The Need For Particles:

because sound is a compression wave, it can only travel through a medium that contains

particles that can be forced closer together or further apart. Sound cannot be

transmitter in a vacuum because there are no particles to push closer together

or spread out. As sound travels through a medium, some of its energy is

absorbed by the particles in the medium and is not transmitted to neighbouring

particles.

Speed Of Sound:

The speed of sound depends on how close the

particles are to each other and how easy they are to push close together. In

liquids and solids, the speed of sound is much greater because the particles

are more closely bound together.

Hear An Echo?:

A knowledge of the speed of sound is

used in sonar. Sonar is used on ships to map the ocean floor, detect schools of

fish.

The Power Of Ultrasound:

Echolocation is used by engineers and it is also used quite a lot in medicine.

Ultrasounds have frequencies higher than human can hear.

CH 9.3

The energy of sound waves is

transformed by your ear into electrical signals that are sent to your brain.

Both of your ears has three distinct parts- the outer ear, inner ear and middle

ear.

Definitions:

Ear Canal: The tube that leads from

the outside of the ear to the eardrum.

Eardrum: A thin piece of stretched

skin inside the ear that vibrates when sound waves reach it.

Membrane: A thin layer of tiny

tissue.

Auricle: The fleshy outside part of

the ear.

Cochlea: The snail-shaped part of the

inner ear. It is lined with tiny hairs that are vibrated by sound and stimulate

the hearing receptors.

Semicircular canals: Three curved

tubes, filled with fluid, in the inner ear that control your sense of balance.

Auditory nerve: A large nerve that sends signals to the

brain from the hearing receptors in the cochlea.

Ossicles: A set of three tiny bones that send vibrations from the eardrum

to the inner ear. They also make the vibrations larger.

Oval Window: An egg shaped hole

covered with a thin tissue. It is the entrance from the middle to outer ear.

Relative Intensity: A measure of how

loud sound is using a sound meter.

Sound Level: The energy of sound that

is an indication of the loudness of a sound.

Decibel (dB): A unit of measurement

of relative sound intensity.

Threshold of hearing: The lowest

level of sound that can be heard by the human ear.

Threshold of pain: The lowest level

of sound that can cause pain to the human ear.

Notes:

Outer Ear:

Funnels the energy of vibrating air through the ear canal to the eardrum.

The eardrum is a thin flap of skin, or membrane, which vibrates in response to

the vibrating air particles.

Inner Ear:

Contains the cochlea and the semicircular canals. When vibrations are

passed through the oval window by the stirrup, the fluid moves the tiny hairs

inside the cochlea. These hairs are attached to the receptor nerve cells that

send messages on their way to the brain through the auditory nerve. The

semicircular canals also contain fluid, however they are not involved in

hearing sound. When you move your head, the fluid in the semicircular canals

moves hairs that send signals to your brain, which tells the brain to keep your

balance.

Middle Ear:

contains three small bones called the hammer, the anvil and the stirrup.

These three, tiny bones pass on the vibrations to the inner ear through the

oval window.

CH 9.4

Definitions:

Electromagnetic spectrum:

Complete range of wave lengths of energy radiated as electric and magnetic

fields.

Radio Waves: Low energy

electromagnetic waves with a much lower frequency and longer wavelength than

visible light.

Infrared Vibrations: Invisible

radiation emitted by all warm objects. You feel infrared radiation as heat.

Visible Light: Very small part of the

electromagnetic spectrum to which our eyes are sensitive.

Ultraviolet Radiation: Invisible

radiation similar to light but with a slightly higher frequency and more

energy.

X-Rays: Hugh energy electromagnetic

waves that can be transmitted through solids and provide information about

their structure.

Gamma Rays: High energy

electromagnetic radiation produced during nuclear reactions. They have no mass

and travel at the speed of light.

Electromagnetic Waves: Electromagnetic

energy that is transmitted as moving electric and magnetic fields. There are

many different types of electromagnetic energy. Eg. Light, microwaves, radio

waves.

Notes:

Waves Without Particles:

Like all waves, electromagnetic waves transmit energy from one place to

another. All electromagnetic waves travel through air at 300 000 000metres per

second. Electromagnet waves can travel through a vacuum.

It’s natural:

Some electromagnetic radiation is emitted by all objects, including the

sun. The higher energy waves, like ultraviolet radiation and X-Rays are emitted

naturally by stars.

What’s the difference:

Some differences between sound waves and electromagnetic waves:

Sound Waves

Electromagnetic Waves

Compression (longitudinal) waves.

Transverse waves.

Travel through all solids, liquids and gases, but are unable to

travel through a vacuum.

Unable to travel through some substances but can travel through a

vacuum.

Speed in air between about 330m/s and 350m/s, depending on the

temperature.

Speed air in about 300 000 000m/s

CH 9.5

Definitions:

Rays: narrow beams of light.

Beam: Wide stream of light rays, all

moving in the same direction.

Reflections: Bouncing off the surface

of a substance.

Luminous: Releasing its own light.”

Scattering: Describes light sent in

many directions by small particles within a substance.

Transparent: Describes a substance

that allows most light to pass through it. Objects can be seen clearly through

transparent substances.

Translucent: Allowing light to come

through imperfectly, as in frosted glass.

Opaque: Describes a substance that

does not allow any light to pass through it.

Notes:

Light travels in straight lines as it travels through empty space or

through a uniform substance such as air or water. A stream of light rays is

called a beam.

Crossing Boundaries:

When light meets a boundary between two different substances, a number of

things can happen;

·

The light may bounce of the surface- reflection.

This allows you to see non-luminous objects.

·

The light might travel through the substance.

Some light is always reflected when light crosses a boundary between two

substances. If most of light travels through the substance the surface is

called transparent. Some substances let just a little bit of light that enable

you to detect objects but you cannot see clearly- this is called translucent.

·

The light may be absorbed by the substance,

transferring the energy to the particles in the substance. The substance is

called opaque.

CHAPTER 10

CH 10.1

Definitions:

Conduction: Transfer of heat

through collisions between particles.

Convection: Transfer of heat through the flow of particles.

Radiation: A method of heat through the flow of particles.

Kinetic Energy: Energy due to the motion of objects.

Insulators: Material that does not let heat move through it.

Convection Currents: Circular

movement that occurs when warmer, less dense fluid particles rise and cooler,

denser fluid particles sink.

Radiant Heat: Heat that is

transferred from one place to another by radiation.

Notes:

Conduction:

The transfer of heat through a substance as a result of neighbouring

vibrating particles. The particles in the region of high temperature are

vibrating more quickly than those in the region of lower temperature, therefore

have more kinetic energy.

Convention:

Unlike the articles that make up solids, those of liquids and gases are

able to move around. In liquids and gases, heat can be transferred from one

region to another by the actual movement of particles.

Radiation:

heat can be transferred without the presence of only particles at all, as

electromagnetic radiation. Heat transferred in this way is called radiation

heat. Like all electromagnetic radiation, radiant heat can be reflected,

transmitted or absorbed.

CH 10.2

Definitions:

Core Body Temperature: The

operating temperature of an organism, especially near the centre of the body.

Perspiration: The salty fluid

produced by sweat glands under the skin.

Heat Exhaustion: A heat related

illness that occurs when the core body temperature reaches 39°C, due to loss of fluid

and salt from the body.

Notes:

The energy needed to keep your core body temperature at 37°C (a healthy core body

temperature) is converted from the chemical energy in food.

CH 10.3

Definitions:

Electric Circuit: A path for

electrons to follow, consisting of a power supply, one or more loads, and

conductors joining the power supply and loads.

Electric Charge: Physical property of

matter that causes it to experience a force when near other electrically

charged matter. Electric charge can be positive or negative.

Nucleus: Central part of an atom,

made up of protons and neutrons; roundish structure inside a cell that acts as

the control centre for the cell.

Electrons: Negatively charged, very

light particles in an atom. Electrons move around the nucleus of the atom. They

are constantly moving around the nucleus. Each electron carries a negative

electric charge.

Negative Electric Charge: The charge

on an atom or object with more electrons than protons.

Protons: Positively charged particles

found in the nucleus of an atom.

Positive Electric Charge: The charge

on an atom or object with fewer electrons than protons.

Neutrons: Particles with no

electrical charge. Are found in the nucleus of an atom.

Notes:

All mater is made up of atoms. At the centre of each atom is a nucleus.

CH 10.4

Notes:

CIRCUIT DIAGRAMS:

Chapter 6

CH 6.1

Notes:

The model of the atom accepted today consists of a tiny, dense nucleus

, made up of protons and neutrons, which is surrounded by electrons.

CH 6.2:

Definitions:

Isotopes: Atoms of the same

element that differ in the number of neutrons I n the nucleus.

Stable: Describes a nucleus that does

not change spontaneously. The protons and neutrons in the nucleus are held

together strongly.

Unstable: Describes an atom in which

the neutrons and the protons in the nucleus are not held together.

Radioisotopes: A radioactive form of

isotope.

Nuclear Radiation: Radiation from the

nucleus of an atom, consisting of alpha or beta particles, or gamma rays.

Alpha Particles: Positively charged

nuclei of helium atoms, consisting of two protons and two neutrons.

Beta Particles: Charged particles

(positive or negative) with the same size and mass as electrons.

Gamma Rays: High energy

electromagnetic radiation produced during nuclear reactions. They have no mass

and travel at the speed of light.

Half-Life: Time taken for half the

radioactive atoms in a sample to decay; that is, change into atoms of a

different element.

Cosmic-Radiation: Naturally occurring

background from outer space.

Notes:

At the centre of every atom is a tiny, solid core called the nucleus.

Within the nucleus protons and neutrons are usually held together by incredibly

strong forces.

Neutrons and Isotopes:

All atoms of a particular element have the same number of protons. However,

often the number of neutrons in atoms of the same element is different. Such

atoms have the same atomic numbers but different mass numbers.

Naming Isotopes:

In symbol, isotopes are represented as

A= The mass number; the sum of the

number of neutrons and number of protons in the nucleus.

Z= The atomic number; number of protons in the nucleus.

E= The symbol of the element.

Three of a Kind:

The energy emitted by radioactive substances is called nuclear radiation

because it comes from the nucleus.

Alpha Particles:

Alpha particles are helium nuclei that contain two protons and two neutrons.

Alpha particles are positively charged. They cannot travel easily through

materials and could be stopped by a sheet of paper or human skin. They are

extremely dangerous if breathed in, eaten or injected. Their symbol is

Beta Particles:

Beta particles are the same mass and size as electrons, can have a positive

or negative electrics charge and can travel at the speed as high as 99% of the

speed of light. They can penetrate human skin and damage living tissue, their

symbol is

Gamma Rays:

Gamma rays are not particles, but bursts of energy release

after alpha or beta particles are emitted.

The Lives and Half-Lives of Radioisotopes:

The nuclei of different radioactive substances decay at different rates. Some

radioisotopes decay in a few seconds, while others take thousands of years. The

time taken for half of all the nuclei in a sample of a radio tope to disintegrate

or decay is known as its half-life.

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