## Conceptual Physics I, Day 13

 Describe the force between two charges which is the source of all electric phenomena. What do you mean by a conductor? and insulator? What types of materials are conductors? What causes an electric current (amperes) to flow in a wire? What are the parallels between water flow in a pipe circuit and electric current flow in a DC electric circuit? What is Ohm's law? How do you calculate electric current and power in an electric circuit? How is it that a bird can sit on a high voltage transmission line and not be shocked? How does a Van de Graaff generator achieve such high voltages? Why is it dangerous to stand under a tree during a thunderstorm? Why is the lightning more likely to strike the tree than flat earth? Why does the question "How much voltage does it take to be a shock hazard?" not have a straightforward answer? What is the best measure of the severity of a shock? Describe the basic layout of standard U.S. household wiring systems. Why are there two high voltage or "hot" wires? Why are standard U.S. receptacles "polarized" with one wide prong and one narrow prong? What is the function of a fuse or circuit breaker? What is the function of a ground wire? If the ground wire is broken, what indication of this will you get from the operation of the appliance? Is household wiring in series or parallel? Why? Why is it that a small amount of corrosion on an auto battery terminal can prevent the engine from starting? If the auto won't start and you suspect the battery, are the headlights and horn operation a good test of the battery's strength? Why is it that a battery may test at normal voltage even when it is too spent to supply appreciable power to a circuit? What is meant by a "short circuit"? an "open circuit"? *Coulomb's law *Electric force example *Conductors and insulators *Voltage *Current *Resistance *Water circuit analogy *Ohm's law *Power relationship *Voltage law *Current law *Bird on high voltage wire *Van de Graaff generator *Lightning *Electric shock *Voltmeter-Ammeter measurements *Voltmeter *Ammeter *Household wiring *Polarized plugs *Breakers and fuses *Ground wire *Series circuit *Parallel circuit *Auto battery example *Effect on headlights *Short circuit and open circuit
Index
HyperPhysics***** Physics 7110 Go Back

## Conceptual Physics I, Day 14

 What kind of force does a magnetic field exert on a charge? on a current in a wire? on charges in a wire when the wire is moved through the magnetic field? How is electric voltage generated in an electric generator? How is the force which turns an electric motor produced? What useful tasks can be accomplished by a transformer? What are the limitations on the power output of a transformer? How can the ignition coil of an automobile generate the very high voltages to fire the spark plugs from just a 12 volt battery? We talk of point charges as sources of electric field. Is there such a thing as a point magnetic source? Describe the magnetic field from a bar magnet and an electromagnet. Why does the presence of an iron core make an electromagnet much stronger? Why is a hand-cranked generator harder to turn if we are using it to light bulb compared to an unconnected generator? What is the difference between a motor and a generator? Why is your refrigerator most likely to kick out the circuit breaker when it first turns on? Why is the starting current for a motor so much higher than the current when it is running continuously? Describe the basic process of generating electricity at a typical electric power plant. Why are transformers used at the power plant to raise the voltage to very high voltages for transmission cross-country? A voltmeter must be used in parallel with the circuit being measured and the ammeter in series. Describe why and describe the consequences when these conditions are not met. What causes the needle in a moving coil meter to move? The same meter movement can be used in an instrument to measure voltage, current, or resistance by just changing switch positions. Describe how the meter is changed to make each. *Magnetic force *Magnetic field *Magnetic field of the Earth *Generator *Faraday's Law *Electric Motor *Transformer *Ignition coil *Bar Magnet *Electromagnet *Magnetic Field of a Current *Magnetic field of Current Loop *Solenoid *Magnet and Coil *Motional Voltage *Voltmeter *Ammeter *Voltmeter design *Ammeter design
Index
HyperPhysics*****Physics 7110 Go Back