Science

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 DefinitionsSonar: 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 10.1Definitions: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 10.2Definitions: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 10.3Definitions: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 10.4Notes:CIRCUIT DIAGRAMS:                                                 Chapter 6 CH 6.1Notes: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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