Transcript Chapter 19
Chapter 19 Chapter Objectives • Electrical Forces and Charges • Coulomb’s Law • Conductors and Insulators • Charge Polarization • Electric Potential • Electric Energy Storage Warm-Up • If the electrons around an atom’s nucleus are spinning then why don’t they just fly off? Notes on board • http://earthscience.stackexchange.com/questi ons/580/why-does-lightning-strike-from-theground-up Coulomb’s Law You just shocked me! And Lightning View video and complete WS • http://www.bing.com/videos/search?q=youtu be+movie+tesla+electricity+and+static&&view =detail&mid=EA16D35A1622F96C6F67EA16D 35A1622F96C6F67&rvsmid=8E73962D739FB1 09C4558E73962D739FB109C455&FORM=VDF SRV&fsscr=0 • http://www.dailymotion.com/video/xlp2y9_bi ll-nye-static-electricity_tech • Chapter 19 Chapter Objectives • Electrical Forces and Charges • Coulomb’s Law • Conductors and Insulators • Charge Polarization • Electric Potential • Electric Energy Storage Warm-Up • Complete the song line: – Home, home on the_______ Ohm’s Law ohm, ohm on the range where the deer and antelope play…. Practice- Ohm’s Law ALL work will be graded for completion and Accuracy • Calculate the current in a toaster that has a heating element of 15 Ω when connected to a 120-V outlet. • Calculate the current that moves through your fingers (resistance 1000 Ω) when you touch them to the terminals of a 6-V battery. • Calculate the current in the 240-Ω filament of a bulb connected to a 120-V line. Practice • What is the voltage of a circuit with 15 amps of current and 8 ohms of resistance? • A light bulb has a resistance of 4 ohms and a current of 2 A. What is the voltage? • How many ohms of resistance must be present in a circuit that has 120 volts and a current of 10 amps? • An alarm clock draws 0.5A of current when connected to a 120 volt circuit. Calculate its resistance. Chapter 19 Chapter Objectives • Electrical Forces and Charges • Coulomb’s Law • Conductors and Insulators • Charge Polarization • Electric Potential • Electric Energy Storage Warm-Up • Think back to a time of happiness not too long ago…..Christmas. What happens to the string of lights when one bulb goes out!! Circuits Series Parallel Practice- Circuits • Are automobile headlights wired in parallel or in series? What is your evidence? • To connect a pair of resistors so that their combined resistance will be greater than the resistance of either one, should you connect them in series or in parallel? • To connect a pair of resistors so that their combined resistance will be less than the resistance of either one, should you connect them in series or in parallel? • Between current and voltage, which remains the same for a 10-Ω and a 20-Ω resistor in series in a series circuit? Choose one current or voltage. • Between current and voltage, which remains the same for a 10-Ω and a 20-Ω resistor in parallel in a parallel circuit? Choose one current or voltage. Label as series or parallel A B Circuit Lab-16 PTS FOR WORK 4 PTS FOR NEATNESS= 20 TOTAL To draw the circuit you will be provided a sheet of symbols. If your circuit WORKS then the bulb will light up 1. Create and draw a series circuit with ONE bulb. 1. 2. 3. 2. Have your teacher approve both. (2pts). Pics must have voltage and current arrows. Your teacher will check the value for current. Use that value and the voltage value given on the battery to calculate resistance. (2pts) SHOW WORK Now Create and draw a series circuit with TWO bulbs. 1. 2. 3. Have your teacher approve both. (2pts) Pics must have voltage and current arrows Your teacher will check the value for current. Use that value and the voltage value given on the battery to calculate resistance. (2pts) SHOW WORK What happened to the resistance as you added the extra bulb? Does this make sense, WHY? 3. Create and draw a parallel circuit with TWO bulb. 1. 2. 3. 4. Have your teacher approve both. (2pts) Pics must have voltage and current arrows Your teacher will check the value for current. Use that value and the voltage value given on the battery to calculate resistance. (2pts) SHOW WORK Now Create and draw a parallel circuit with THREE bulbs. 1. 2. 3. Have your teacher approve both. (2pts) Pics must have voltage and current arrows Your teacher will check the value for current. Use that value and the voltage value given on the battery to calculate resistance. (2pts) SHOW WORK What happened to the resistance as you added the extra bulb? Does this make sense, WHY? Demo Day 1. Tesla Coil 1. 2. 3. 4. 5. 6. 7. 8. 2. Draw the apparatus. Label the primary and secondary coils. Who invented this coil? What does a step-up transformer do? Explain how the Tesla coil steps-up. The primary coil has high current and high voltage, does this make sense? The secondary coil has high voltage and low current, how can this be true? Does voltage, current or resistance kill!? Van de Graaff 1. 2. 3. 4. 5. 6. 7. 8. Draw the apparatus. Label the charges on the apparatus. Who invented this device? How far away should one have their electronic device? Why should people with pacemakers stay away from this device? Explain how the Van de Graaff machine works. Explain the science behind each demo. The voltage is 200,000V but the current is only 3.0x10^-6. How can this be true? Solve for the resistance to find out. 8th Period I do not appreciate the way you behaved on Thursday during our circuit lab nor did I appreciate the way you behaved during Demo Day. I understand that it is not all of you. However, here is what the consequences will be: 1. Today we have a Study Guide to complete. You will do this on your own WITHOUT help from your peers. When you are finished you are expected to complete the section reviews on page 687, 696, and 705. IT IS DUE AT THE END OF THE PERIOD. 2. We will no longer have labs, you will complete book work instead. More of you have proven untrustworthy during labs when my attention needs to be directed at one group.