Electricity & Magnetism Static, Currents, Circuits Magnetic Fields & Electro Magnets Motors & Generators

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Slide 2 Electricity & Magnetism Static, Currents, Circuits Magnetic Fields & Electro Magnets Motors & Generators Slide 3 Atoms Have neutrons, protons, and electrons. Have neutrons, protons, and electrons. Protons are positively charged Protons are positively charged Electrons are negatively charged Electrons are negatively charged Slide 4 Electrons Are located on the outer edges of atomsthey can be moved. Are located on the outer edges of atomsthey can be moved. A concentration of electrons in an atom creates a net negative charge. A concentration of electrons in an atom creates a net negative charge. If electrons are stripped away, the atom becomes positively charged. If electrons are stripped away, the atom becomes positively charged. Slide 5 Electrons Are located on the outer edges of atomsthey can be moved. valence Are located on the outer edges of atomsthey can be moved. valence A concentration of electrons in an atom creates a net negative charge. anion A concentration of electrons in an atom creates a net negative charge. anion If electrons are stripped away, the atom becomes positively charged. cation If electrons are stripped away, the atom becomes positively charged. cation Slide 6 + - + + + + The world is filled with electrical charges: + + + + + - - - - - - - - - Slide 7 What is this electrical potential called? -- - - - - - + + + + + Slide 8 Static Electricity The build up of an electric charge on the surface of an object. The build up of an electric charge on the surface of an object. The charge builds up but does not flow. The charge builds up but does not flow. Static electricity is potential energy. It does not move. It is stored. Static electricity is potential energy. It does not move. It is stored. Slide 9 Static Discharge Occurs when there is a loss of static electricity due to three possible things: Occurs when there is a loss of static electricity due to three possible things: Friction rubbing (direct contact) Friction rubbing (direct contact) Conduction direct contact Conduction direct contact Induction through an electrical field (not direct contact) Induction through an electrical field (not direct contact) Slide 10 Electricity that moves Current: The flow of electrons from one place to another. Current: The flow of electrons from one place to another. Measured in amperes (amps) Measured in amperes (amps) Kinetic energy Kinetic energy Slide 11 How can we control currents? With circuits. With circuits. Circuit: is a path for the flow of electrons. We use wires. Circuit: is a path for the flow of electrons. We use wires. Slide 12 There are 2 types of currents: Direct Current (DC) Where electrons flow in the same direction in a wire. Direct Current (DC) Where electrons flow in the same direction in a wire. The devices you plug in to a wall The devices you plug in to a wall Slide 13 2nd type of current: Alternating Current (AC) electrons flow in different directions in a wire Alternating Current (AC) electrons flow in different directions in a wire The current in buildings and houses The current in buildings and houses Slide 14 There are 2 types of circuits: Series Circuit: the components are lined up along one path. If the circuit is broken, all components turn off. Series Circuit: the components are lined up along one path. If the circuit is broken, all components turn off. Slide 15 Series Circuit Slide 16 2 nd type of circuit: Parallel Circuit there are several branching paths to the components. If the circuit is broken at any one branch, only the components on that branch will turn off. Parallel Circuit there are several branching paths to the components. If the circuit is broken at any one branch, only the components on that branch will turn off. Most houses and buildings are wired this way Most houses and buildings are wired this way Slide 17 Parallel Circuit Slide 18 Conductors vs. Insulators Conductors material through which electric current flows easily. Conductors material through which electric current flows easily. Insulators materials through which electric current cannot move. Insulators materials through which electric current cannot move. Slide 19 Conductors vs. Insulators Conductors material through which electric current flows easily. Conductors material through which electric current flows easily. Conductor makes music flow from the orchestra Conductor makes music flow from the orchestra Conductor makes train flow smoothly down tracks Conductor makes train flow smoothly down tracks Insulators materials through which electric current cannot move. Insulators materials through which electric current cannot move. Slide 20 Examples Conductors: Conductors: Metal Metal Water Water Insulators: Insulators: Styrofoam Rubber Plastic Paper Slide 21 SEMICONDUCTORS Semiconductors are materials that essentially can be conditioned to act as good conductors, or good insulators, or anything in between. Common elements such as carbon, silicon, and germanium are semiconductors. Can you find them on the Periodic Table? What do they have in common? Silicon is the best and most widely used semiconductor. Slide 22 Diodes Diode device is a one way valve that controls the flow of electricity LED lights are the best example LED = Light Emitting Diode Transistors are used to amplify electrical signals (like in a radio) Slide 23 What is Resistance? The opposition to the flow of an electric current, producing heat. The opposition to the flow of an electric current, producing heat. The greater the resistance, the less current gets through. The greater the resistance, the less current gets through. Good conductors have low resistance. Good conductors have low resistance. Measured in ohms. Measured in ohms. Slide 24 What Influences Resistance? Material of wire aluminum and copper have low resistance Material of wire aluminum and copper have low resistance Thickness the thicker the wire the lower the resistance Thickness the thicker the wire the lower the resistance Length shorter wire has lower resistance Length shorter wire has lower resistance Temperature lower temperature has lower resistance Temperature lower temperature has lower resistance Slide 25 What is Voltage? The measure of energy given to the charge flowing in a circuit. The measure of energy given to the charge flowing in a circuit. The greater the voltage, the greater the force or pressure that drives the charge through the circuit. The greater the voltage, the greater the force or pressure that drives the charge through the circuit. Slide 26 Difference b/t Volts, Amps, Ohms Difference b/t Volts, Amps, & Ohms Example you could say that Example you could say that Current (amps) measure how much water comes out of a water pipe. (amount) Current (amps) measure how much water comes out of a water pipe. (amount) Voltage (volts) measure how much pressure is behind the water. (force) Voltage (volts) measure how much pressure is behind the water. (force) Resistance (ohms) measures the friction against the inside of the water pipe Resistance (ohms) measures the friction against the inside of the water pipe Slide 27 Slide 28 Ohms Law Resistance = Voltage / Current Resistance = Voltage / Current Ohms = Volts / Amps Ohms = Volts / Amps Slide 29 Practice with Ohms Law OhmsVoltsAmps 410025 1515010 23015 9455 6488 Slide 30 Difference b/t volts & watts If volts x amps = watts Then force of electricity x amount of electricity how powerful it is Remember,how much water? P = w / t how much time? Slide 31 Properties of Magnets All magnets have two areas of strongest force, called poles. All magnets have two areas of strongest force, called poles. Each magnet has one north pole and one south pole. Each magnet has one north pole and one south pole. Like poles repel, and opposite poles attract. Like poles repel, and opposite poles attract. The magnetic region where you can feel the force is called a magnetic field. The magnetic region where you can feel the force is called a magnetic field. Slide 32 Magnetic Materials What makes some things magnetic, while other things cant be magnetized? What makes some things magnetic, while other things cant be magnetized? Spinning electrons cause small magnetic fields around each atom. Spinning electrons cause small magnetic fields around each atom. Magnetic materials have atoms whose magnetic fields can be lined up in the same direction. Magnetic materials have atoms whose magnetic fields can be lined up in the same direction. Areas where atoms magnetic fields line up are called magnetic domains. Areas where atoms magnetic fields line up are called magnetic domains. magnetic domain Randomly arranged domains = No magnet! Randomly arranged domains = No magnet! Magnetic domains lined up = Magnet! Magnetic domains lined up = Magnet! Slide 33 The Earth is a magnet! magnetic north pole geographic north pole magnetic south pole magnetic south pole geographic south pole Magnetic lines of force around the earth are like the field lines around a giant bar magnet. Magnetic lines of force around the earth are like the field lines around a giant bar magnet. The magnetic north pole and the geographic north pole are not located in the same place! The magnetic north pole and the geographic north pole are not located in the same place! The north pole of a compass points to the earths magnetic north pole. The north pole of a compass points to the earths magnetic north pole. Slide 34 Electricity to Magnetism In 1820, H.C. Oersted discovered that an electric current flowing through a wire had a magnetic field around it. In 1820, H.C. Oersted discovered that an electric current flowing through a wire had a magnetic field around it. Electricity can cause magnetism! Electricity can cause magnetism! Electromagnets are powerful magnets that can be turned on and off. Electromagnets are powerful magnets that can be turned on and

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