Presentation on theme: "Mechanical Thermal Chemical Nuclear Electrical Radiant Types of Energy Table of Contents."— Presentation transcript:
Mechanical Thermal Chemical Nuclear Electrical Radiant Types of Energy Table of Contents
Mechanical Energy Review ME = PE + KE KE = ½ m v 2 greatest at position 2 GPE = mgh greatest at position 1 and 5 4
Thermal Energy The sum of the kinetic and potential energy of all the particles in an object is the thermal energy of the object. 6.1
Matter in Motion The faster they move, the more kinetic energy they have. This figure shows that particles move faster in hot objects than in cooler objects. 6.1 Temperature and Heat
Transfer Thermal Energy Thermal energy is transferred when one end of a metal spoon is heated by a Bunsen burner. The kinetic energy of the particles near the flame increases. 6.2 Transferring Thermal Energy
Kinetic energy is transferred when these particles collide with neighboring particles. 6.2 Transferring Thermal Energy As these collisions continue, thermal energy is transferred from one end of the spoon to the other end of the spoon. Transfer Thermal Energy
Radiant Energy and Matter Different materials on Earth absorb radiation in different amounts resulting in uneven heating. Sea breezes and Land breezes are examples of this. Natural convection currents are created. 6.2 Transferring Thermal Energy
Internal Combustion Engines A car engine is an internal combustion engine 6.3 Using Heat Each cylinder contains a piston that moves up and down (a stroke). The heated material in the cylinders expands forcing the piston down. As exhaust gases are released, the piston comes up. As the crankshaft moves with the piston, it turns vital parts of the car.
Internal Combustion Engines 6.3 Using Heat
Chemical energy comes from energy release when chemical bonds are broken or formed. When we eat, we break the bonds in our food to release energy to be used by our body. Same goes for chemical fuel used for other reasons. Chemical Energy
Compared to other fuels such as wood, the chemical energy that is stored in fossil fuels is more concentrated. For example, burning 1 kg of coal releases two to three times as much energy as burning 1 kg of wood. Chemical Energy Sources 9.1
Petroleum is a highly flammable liquid formed by decayed ancient organisms, such as microscopic plankton and algae. It is one of the fossil fuels. The key ingredient to fossil fuel is a carbon hydrogen bond called a hydrocarbon. Carbon is found in all living and once living things. Petroleum 9.1 Fossil Fuels
9.2 Nuclear Energy Nuclear Energy is a type of chemical energy A nuclear power plant generates electricity using the energy released in nuclear fission. The sun generates energy transferred as light by nuclear fusion.
9.2 Nuclear Fission When a neutron strikes the nucleus of a U-235 atom, the nucleus splits apart into two smaller nuclei. In the process -two or three neutrons are emitted, -smaller nuclei are called fission products of barium and krypton are created, -and energy is released.
9.2 Nuclear Fusion Thermonuclear fusion is the joining together of small nuclei at high temperatures. 2 hydrogen atoms fuse to form a helium atom of less mass The mass lost turns into energy by E=mc 2
Atoms contain particles called protons, neutrons, and electrons. Protons are positively charged Electrons have a negative charge, Neutrons have no electric charge. Electrical Energy 7.1
When you walk on the carpet, electrons are transferred from the carpet to the soles of your shoes. Static Electricity 7.1 Electric Charge Your shoe soles become negatively charged. The carpet lost electrons and is positively charge. The accumulation of excess electric charge on an object is called static electricity.
Lightning is a large static discharge. Lightning 7.1 Static Charge A static discharge is a transfer of charge between two objects A thundercloud is a mighty generator of static electricity. As air masses move and swirl in the cloud, areas of positive and negative charge build up.
Eventually, enough charge builds up to cause a static discharge between the cloud and the ground. Lightning 7.1 Static Charge As the electric charges move through the air, they collide with atoms and molecules. These collisions cause the atoms and molecules in air to emit light.
Current and Voltage Difference The net movement of electric charges in a single direction is an electric current. 7.2 Electric Current When an electric current flows in the wire, electrons drift in the direction that the current flows. Electric current is measured in amperes (Amps).
Voltage Difference Electric charge flows from higher voltage to lower voltage. A voltage difference is related to the force that causes electric charges to flow. Voltage difference is measured in volts. 7.2 Electric Current
Law of conservation of charge, charge can be transferred, but it cannot be created or destroyed. Whenever an object becomes charged, electric charges have moved from one place to another. Conservation of Charge 7.1 Electric Charge
A material in which electrons are able to move easily is a conductor. Conductors 7.1 Electric Charge The best electrical conductors are metals. The atoms in metals have electrons that are able to move easily through the material.
A material in which electrons are not able to move easily is an insulator. Insulators 7.1 Electric Charge Electrons are held tightly to atoms in insulators. Most plastics are insulators. The plastic coating around electric wires prevents a dangerous electric shock when you touch the wire.
Electric Circuits 7.2 Electric Current A closed path that electric current follows is a circuit. If the circuit is broken by removing the battery, or the light bulb, or one of the wires, current will not flow.
Resisting the Flow of Current Resistance is the tendency for a material to oppose the flow of electrons, changing electrical energy into thermal energy and light. 7.2 Electric Current Resistance is measured in ohms ( ). Depends on temperature, length, and diameter: hotter, longer, thinner increases resistance
Ohm's Law 7.2 Electric Current According to Ohm's law, the current in a circuit equals the voltage difference divided by the resistance. The voltage difference, resistance, and current in a circuit are related. Ohm's law provides a way to measure the resistance of objects and materials. First the equation above is written as: I = V/R
Series Circuits One kind of circuit is called a series circuit. In a series circuit, the current has only one loop to flow through. 7.3 Electrical Energy Series circuits are used in flashlights and some holiday lights.
Parallel Circuits Houses are wired with parallel circuits. 7.3 Electrical Energy Parallel circuits contain two or more branches for current to move through. The current can flow through both or either of the branches.
Household Circuits The main switch and circuit breaker or fuse box serve as an electrical headquarters for your home. 7.3 Electrical Energy Parallel circuits branch out from the box to wall sockets, major appliances, and lights.
Household Circuits 7.3 Electrical Energy To protect against overheating of the wires, all household circuits contain either a fuse or a circuit breaker. The rate at which electrical energy is converted to another form of energy is the electric power.
Magnetic Domains 8.1 Magnetism Magnetic material contains domains of enormous number of atoms that align their charges. Domains are also aligned creating a magnetic field with polar ends.
A magnetic field exerts a force on other magnets and objects made of magnetic materials. Magnetic Field 8.1 Magnetism The magnetic field is strongest close to the magnet and weaker far away. The field also has direction.
Magnetic poles are where the magnetic force exerted by the magnet is strongest. Magnetic Poles 8.1 Magnetism Like poles (ie.2 north poles or 2 south poles) repel each other. Opposite poles (ie. north poles and south poles) attract each other.
Earth’s Magnetic Field 8.1 Magnetism The earth is a large magnet due to a solid inner core of iron and nickel surrounded by a spinning layer of liquid iron and nickel.
A compass can help determine direction because the north pole of the compass needle points to the northern geographic pole which is actually a south magnet pole. Earth’s Magnetic Field 8.1 Magnetism
Moving Charges and Magnetic Fields It is now known that moving charges, like those in an electric current, produce magnetic fields. Around a current- carrying wire the magnetic field lines form circles. 8.2 Electricity and Magnetism
Electromagnets A single wire wrapped into a cylindrical wire coil is called a solenoid. 8.2 Electricity and Magnetism An electromagnet is a temporary magnet made by wrapping a wire coil carrying a current around an iron core. The magnetic field inside the loop is stronger than the field around a straight wire.
Step 1. When a current flows in the coil, the magnetic forces between the permanent magnet and the coil cause the coil to rotate. 8.2 Electricity and Magnetism An electric motor is a device that changes electrical energy into mechanical energy. Electric Motors
Making the Motor Spin Step 2. In this position, the brushes are not in contact with the commutator and no current flows in the coil. 8.2 Electricity and Magnetism The inertia of the coil keeps it rotating.
Making the Motor Spin Step 3. The commutator reverses the direction of the current in the coil. 8.2 Electricity and Magnetism This flips the north and south poles of the magnetic field around the coil.
Making the Motor Spin Step 4. The coil rotates until its poles are opposite the poles of the permanent magnet. 8.2 Electricity and Magnetism The commutator reverses the current, and the coil keeps rotating.
Generators A generator uses electromagnetic induction to transform mechanical energy into electrical energy. In this type of generator, a current is produced in the coil as the coil rotates between the poles of a permanent magnet. 8.3 Producing Electric Current
Generating Electricity for Home s 8.3 Producing Electric Current The rotating magnets are connected to a turbine, a large wheel that rotates when pushed by water, wind, or steam.
Direct and Alternating Currents 8.3 Producing Electric Current A battery produces a direct current. Direct current (DC) flows only in one direction through a wire. Power companies produce alternating current (AC) reverses the direction of the current in a regular pattern.
Transmitting Electrical Energy 8.3 Producing Electric Current When the electric energy is transmitted along power lines, some of the electrical energy is converted into heat due to the electrical resistance of the wires. The electrical resistance and heat production increases as the wires get longer.
Transmitting Electrical Energy 8.3 Producing Electric Current One way to reduce the heat produced in a power line is to transmit the electrical energy at high voltages, typically around 150,000 V. Electrical energy at such high voltage cannot enter your home safely, nor can it be used in home appliances. A transformer is used to decrease the voltage.
Transformers 8.3 Producing Electric Current A transformer is a device that increases or decreases the voltage of an alternating current. A transformer is made of a primary coil and a secondary coil. These wire coils are wrapped around the same iron core.
Transformers 8.3 Producing Electric Current A transformer that increases the voltage so that the output voltage is greater than the input voltage. A transformer that decreases the voltage so that the output voltage is less than the input voltage.
Transmitting Alternating Current 8.3 Producing Electric Current This figure shows how step-up and step-down transformers are used in transmitting electrical energy from power plants to your home.
A wave is a repeating disturbance or movement that transfers energy through matter or space The Nature of Waves The waves don’t carry matter along with them. Only the energy carried by the waves moves forward. A wave will travel only as long as it has energy to carry.
Mechanical Waves Mechanical waves are waves that travel through matter. The matter the waves travel through is called a medium. The medium can be a solid, a liquid, a gas, or a combination of these The Nature of Waves
A transverse wave moves up and down Types of Mechanical of Waves A compressional wave moves back and forth.
Water Waves a mechanical wave of a combination of transverse and compression action Examples of Mechanical Waves Seismic Waves are also a combination of both actions that go through the Earth’s crust
The Parts of a Wave A transverse wave has alternating high points, called crests, and low points, called troughs Wave Properties
Wavelength A wavelength is the distance between one point on a wave and the nearest point just like it. For transverse waves the wavelength is the distance from crest to crest or trough to trough Wave Properties
Frequency and Period The frequency of a wave is the number of wavelengths that pass a fixed point each second. You can find the frequency of a transverse wave by counting the number of crests or troughs that pass by a point each second Wave Properties Frequency is expressed in hertz (Hz).
Calculating Wave Speed You can calculate the speed of a wave represented by v by multiplying its frequency times its wavelength Wave Properties
Amplitude of Transverse Waves 10.2 Wave Properties The amplitude of any transverse wave is the distance from the crest or trough of the wave to the rest position of the medium.
The Law of Reflection The beam striking the mirror is called the incident beam The Behavior of Waves The beam that bounces off the mirror is called the reflected beam.
Refraction Refraction is the bending of a wave caused by a change in its speed as it moves from one medium to another The Behavior of Waves
Diffraction Waves also can be diffracted when they pass through a narrow opening The Behavior of Waves After they pass through the opening, the waves spread out and bend.
Interference When two or more waves overlap and combine to form a new wave, the process is called interference. Interference occurs while two waves are overlapping The Behavior of Waves
Constructive Interference In constructive interference, the waves add together The Behavior of Waves The amplitude of the new wave that forms is equal to the sum of the amplitudes of the original waves.
Destructive Interference In destructive interference, the waves subtract from each other as they overlap The Behavior of Waves This happens when the crests of one transverse wave meet the troughs of another transverse wave.
Electromagnetic waves are made by vibrating electric charges and can travel through space where matter is not present. Instead of transferring energy from particle to particle, electromagnetic waves travel by transferring energy between vibrating electric and magnetic fields. Electromagnetic Waves 12.1 What are electromagnetic waves?
All electromagnetic waves travel at 300,000 km/s in the vacuum of space. The speed of electromagnetic waves in space is usually called the “speed of light.” Wave Speed 12.1 What are electromagnetic waves? As the frequency increases, the wavelength becomes smaller.
Energy carried by a wave depends on its amplitude and not its frequency. Waves and Particles 12.1 What are electromagnetic waves? Albert Einstein stated electromagnetic waves can behave as a particle, called a photon, whose energy depends on the frequency of the waves.
A Range of Frequencies Electromagnetic waves can have a wide variety of frequencies. The entire range of electromagnetic wave frequencies is known as the electromagnetic spectrum The Electromagnetic Spectrum
Visible Light Visible light is the range of electromagnetic waves that you can detect with your eyes. Visible light has wavelengths around 750 billionths to 400 billionths of a meter The Electromagnetic Spectrum
Radiant Energy and Light The Behavior of Light 13.1 Light is the result of radiant energy traveling in electromagnetic waves that hit materials and excite the material’s electrons. Those electrons move farther away from the nucleus When it returns the electron gives off photons of electromagnetic waves.
The Law of Reflection Because light behaves as a wave, it obeys the law of reflection. According to the law of reflection, light is reflected so that the angle of incidence always equals the angle of reflection. The Behavior of Light 13.1
Colors An object’s color depends on the wavelengths of light it reflects You know that white light is a blend of all colors of visible light. This image shows white light striking a green leaf. Only the green light is reflected to your eyes. Light and Color
Refraction and Rainbows Like prisms, rain droplets also refract light. The Behavior of Light The refraction of the different wavelengths can cause white light from the Sun to separate into the individual colors of visible light Refraction is caused by a change in the speed of a wave when it passes from one material to another.
Light and the Eye In a healthy eye, light enters and is focused on the retina, an area on the inside of your eyeball The retina is made up of two types of cells that absorb light. Light and Color These cells absorb light energy, chemical reactions convert light energy into nerve impulses that are transmitted to the brain.
Light and the Eye 13.2 One type of cell in the retina, called a cone, allows you to distinguish colors and detailed shapes of objects and are most effective in daytime vision. Light and Color The second type of cell, called a rod, is sensitive to dim light and is useful for night vision. Red, green, and blue are the primary colors of light. When mixed together in equal amounts they produce white light.
Mixing Colors A pigment is a colored material that is used to change the color of other substances The color of a pigment results from the different wavelengths of light that the pigment reflects. Light and Color A primary pigment’s color depends on the color of light it reflects. If all the primary light colors are reflected in equal amounts, the object appears white.
The image formed when an object is placed by a mirror changes depending on its position in relation to the mirror’s focal point. Mirrors 14.1 Mirrors The mirrors are often used to magnify objects. If the surface of a mirror is curved inward, it is called a concave mirror.
A mirror that curves outward like the back of a spoon is called a convex mirror. Convex Mirrors 14.1 Mirrors Objects tend to appear smaller and farther away such as in rear view and side mirrors of cars.
What is a lens? A lens is a transparent material with at least one curved surface that causes light rays to bend, or refract, as they pass through. The image that a lens forms depends on the shape of the lens. Like curved mirrors, a lens can be convex or concave Lenses The type of image a lens forms depends on where the object is relative to the focal point.
Convex Lenses A convex lens is thicker in the middle than at the edges Lenses When the candle is more than two focal lengths away from the lens, its image is real, reduced, and upside down.
Concave Lenses A concave lens is thinner in the middle and thicker at the edges Lenses The image is always virtual, upright, and smaller than the actual object is.
Focusing on Near and Far As an object gets farther from your eye, the focal length of the lens has to increase Lenses The muscles around the lens stretch it so it has a less convex shape.
Focusing on Near and Far 14.2 Lenses But when you focus on a nearby object, these muscles make the lens more curved, causing the focal length to decrease.
Vision Problems— Farsightedness If you can see distant objects clearly but can’t bring nearby objects into focus, then you are farsighted Lenses
Farsightedness To correct the problem, convex lenses cause incoming light rays to converge before they enter the eye Lenses
Astigmatism Another vision problem, called astigmatism occurs when the surface of the cornea is curved unevenly Lenses When people have astigmatism, their corneas are more oval than round in shape. Astigmatism causes blurry vision at all distances.
Nearsightedness If you have nearsighted friends, you know that they can see clearly only when objects are nearby Lenses When a nearsighted person looks at distant objects, the light rays from the objects are focused in front of the retina.
Nearsightedness A concave lens in front of a nearsighted eye will diverge the light rays so they are focused on the retina Lenses