| Question | Answer |
| Circuit breakers | Use magnets or bimetallic strips to open the switch. Used instead of fuses because don't have to be replaced every time circuit broken. Just switched back to on position. |
| Short Circuit | When insulation wears away and wires touch to create smaller circuit. Large current because of less resistance. |
| Fuses | Prevent overloading in circuits. Fuse explodes if wires overload, prevents fires |
| Lines | feed electricity into a home, low in resistance. Connected to wall outlets |
| Internal resistance | Resistance inside battery |
| Equivalent resistance for a pair of equal resistors in parallel | 1/2 the value of either resistor |
| Equivalent resistance | Value of the single resistor that would comprise the same load to the battery or power source. Total resistance. |
| Schematic diagrams | Symbols used to represent cerntain cicuit elements |
| Overall resistance | Greater number of branches, less resistance. |
| Total current in parallel | Divides among parallel branches. Ohm's law applies separately. Sum of currents in branches. |
| Total voltage in series | Divides among individual electric devices. Sum of voltage drops = total voltage supplied by the source. |
| Total resistance in series | Sum of resistors. (Ohm's law applies to each device) |
| Current in series | = for all resistors |
| In Parallel Circuit | Branches where each is a separate path for flow of electrons |
| In Series Circuits | Single pathway for electron flow between terminals of battery/wall socket. Break anywhere stops electricity in all resistors. |
| Circuit | Complete path from the positive terminal to negative terminal |
| Watts | Measure of electric power. 1W = 1A x 1V |
| Electric power | Rate at which electric energy converted into another form |
| Source of electrons in a circuit | From material itself. Not from outlet or battery. |
| Speed of electrons in ac | Do not move at all, because move back and forth. Instead vibrate. |
| Speed of electrons in dc | Electrons do not move very fast, because motion is random |
| Diode | Tiny electronic device that acts as a one-way valve to allow electron flow in one direction. Allows use of ac instead of batteries. Converts ac to dc. Used with a capacitor to maintain continuous current. |
| Power-hungry appliances | 220-240 V. Possible because 3 wire outlets. |
| ac in common house outlet | Voltages alter back and forth at 60 Hz. Voltage = 120 V |
| Alternating Current | ac. Electrons go first in one direction, than the opposite. Accomplished by alternating polarity of voltage at voltage source. |
| Direct Current | dc. Flow of charge always in 1 direction. In batteries, terminals always same charge. |
| 3 prong plugs | 1 prong +, 1 prong -, 1 prong neutral, for grounding. If live wire comes in contact with a metal surface, current to ground instead of shocking you. |
| Birds on high voltage wires | No effects because no voltage difference. Touch nothing else of different voltage. |
| Wet body and electricity | Resistance less with wetness. Ions in water transfer energy more easily. |
| Electric shock | Result of current passing through body, but depends on voltage |
| Ohm | Unit of electric resistance |
| Higher the temperature | Greater the resistance |
| Longer the wire | Greater the resistance |
| Thicker the wire | Less the resistance |
| Electric resistance | Resistance conductor offers to the flow of charge. Depends on conductivity of material, thickness and length of wire |
| Voltage of home outlets | 120 V alternating potential difference |
| Generators | Convert mechanical energy to electric energy |
| Dry/wet cells | Energy released in chemical reaction, converted to electric energy |
| Batteries | Arrangements of 2 or more cells |
| 3 voltage sources | Dry cells, wet cells, generators |
| Voltage Source | Something that provides a potential difference |
| Amperes | Measure electric current. 1 A = 1C / 1Sec |
| Conduction in fluids | Positive and negative ions can carry charge |
| Conduction Electrons | Electrons that carry charge through a circuit |
| Electric current | Flow of electric charge, electrons carry charge through circuit |
| Potential difference | Difference in voltage across the ends of a conductor |
| When does flow of charge happen? | Potential Difference |
| 1 / R equivalent = 1/R1 + 1/R2 +... | 1 / Resistance in parallel = Sum of the inverses of the resistors |
| R equivalence = R 1 + R2 +... | Resistance in series = sum of resistors |
| P = IV | Electric Power = Current x Voltage. 1 watt = 1 ampere x 1 volt |
| V = IR | Ohm's Law. Voltage = Current x Resistance. 1 ampere = 1 volt / 1 ohm |
51 cards - created apr 7, 7:46pm