Introduction to Electricity Static Electricity and Electrical charge

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<ul><li> Slide 1 </li> <li> Introduction to Electricity Static Electricity and Electrical charge </li> <li> Slide 2 </li> <li> Slide 3 </li> <li> Atoms and charge Atoms are made of protons, neutrons and Electrons. Protons- positive Neutrons- neutral Electrons- negative Charges of particles </li> <li> Slide 4 </li> <li> Law of Electrical charges Like charges repel and opposite charges attract. The force between charged objects is Electrical force. </li> <li> Slide 5 </li> <li> Slide 6 </li> <li> Slide 7 </li> <li> Electrical force Strength of electrical force determined by Size of the charge -greater charge = more force Distance from charge- close=greater </li> <li> Slide 8 </li> <li> Charging atoms Objects can become charged because Atoms can either gain or lose electrons Gain electrons = negative charge Lose electrons= positive charge Atoms cant lose protons or neutrons!! </li> <li> Slide 9 </li> <li> Charge by friction Rubbing 2 objects together to separate Positive and negative charges. </li> <li> Slide 10 </li> <li> Charging by conduction When electrons are transferred from one Object to another by direct contact </li> <li> Slide 11 </li> <li> Charge by induction Occurs when charges in uncharged object Are rearranged without direct contact With charged object </li> <li> Slide 12 </li> <li> Conservation of charge Charges are not created nor destroyed, Just moved from atom to atom </li> <li> Slide 13 </li> <li> Detecting charge Electroscope can detect if an object is charged </li> <li> Slide 14 </li> <li> Moving electrical charges Materials are divided into 2 groups based On how easily a charge can travel through it Conductors or Insulators </li> <li> Slide 15 </li> <li> Conductors Allow charges to move easily through them Electrons in metals are free to move about Used to make wires Not always metals (water) </li> <li> Slide 16 </li> <li> Insulators Materials that do not allow easy charge movement Electrons are tightly bound Used to coat conductors to prevent shock </li> <li> Slide 17 </li> <li> Static electricity Build-up of electrical charge Charges are not moving Created by opposite charges </li> <li> Slide 18 </li> <li> Lightning Occurs when charge is separated in cloud And induces opposite charge on the surface </li> <li> Slide 19 </li> <li> Section 2 Electrical energy Batteries uses chemical reactions to Produce electrical energy. </li> <li> Slide 20 </li> <li> Batteries Cells- device that produces an electrical current by converting chemical energy to electrical energy. Battery- uses several cells to make energy </li> <li> Slide 21 </li> <li> Parts of a cell Batteries contain electrolytes (a mixture of chemicals) Chemical reaction in electrolytes convert chemical energy to electrical energy </li> <li> Slide 22 </li> <li> Simple cell Pair of electrodes made from 2 different conducting metals are In contact with electrolyte. Electrode- part of a cell through which charges enter and exit. </li> <li> Slide 23 </li> <li> Types of cells Dry cells- use solid or paste-like electrolyte Wet cells- use sulfuric acid as electrolyte </li> <li> Slide 24 </li> <li> Potential difference Energy per unit charge expressed in volts Chemical reaction causes difference in charge between electrodes. More cells = more potential difference </li> <li> Slide 25 </li> <li> Other ways to produce electrical energy Photocells- solar panel converting light to Electrical energy Thermocouple- thermal energy converted To electrical energy </li> <li> Slide 26 </li> <li> Section 3 Electric Current Current- rate at which charge flows Ampire (AMP)- unit for current Voltage- difference between energy per unit charge </li> <li> Slide 27 </li> <li> AC/DC AC or Alternating current- current can flow any direction in a wire home wiring DC or Direct current- current only flows in one direction. Batteries, flashlights </li> <li> Slide 28 </li> <li> Voltage and resistance US households supply a voltage of 120 V Resistance opposition of flow of electrons Think of this as electrical friction. Resistance is expressed in OHMs As resistance increases, current decreases </li> <li> Slide 29 </li> <li> Factors that affect resistance Conductor type- copper good, iron bad Thickness of wire thicker wires decrease resistance Length of wire- longer wires increase resistance Temperature- higher temps = higher resistance </li> <li> Slide 30 </li> <li> Ohms Law Shows voltage, current and resistance Are related with the following equation V = I x R R = V / I I = V / R V = voltage R= Resistance I= Current </li> <li> Slide 31 </li> <li> Electrical Power The rate at which electrical energy is used To do work. Power (W) = voltage (V) X current (Amps) </li> <li> Slide 32 </li> <li> Power rating Measured in watts for light bulbs and all Electrical appliances and devices Kilowatt-hours for measuring household Electricity use. </li> </ul>

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