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8th gde Electricity
| Question | Answer |
|---|---|
| The basic building blocks of matter | Atoms |
| What are the three particles found in atoms? | Protons (+), neutrons (0), and electrons(-) |
| Which particles are found in the nucleus? | Protons and neutrons |
| Where are electrons found? | In the “electron cloud” outside the nucleus |
| Which is the only particle that moves freely? | Electrons, because they can be “knocked off” the outside of the atom, creating an electric charge. |
| What causes an object to become negatively charged? | Electrons move from another object to that object |
| What causes an object to become positively charged? | Electrons move to another object from that object |
| A charged object is brought near another object or surface, producing an electric charge | Charging by induction |
| Two objects are brought into contact (rubbing/friction), and negative charges move from one to the other, giving both a charge | Charging by conduction |
| Electric charges that are the same do this | Repel |
| Electric charges that are different do this | Attract |
| What are the two types of electricity? | Static and current. |
| The build up of charges in one area due to the gain or loss of electrons when objects rub together is called this | Static Electricity |
| What causes a spark (electric discharge) to “jump?” | The negative charges built up on one object (usually by conduction) are attracted to a conductor with a lower concentration of negative charges. |
| The flow of electrons in a wire | electric current |
| How do electrons behave in current electricity? | They “flow” through a conductor from an area of negative charge to an area of positive charge. |
| Materials like metals that allow electrons to flow easily through them | conductors |
| Materials that resist the flow of electrons | insulators |
| Name some conductors | Most metals, water, the human body |
| Name some insulators | Plastic, wood, glass, rubber |
| What example of electric current did we study? | A lit flashlight |
| What source of electric current did we build in lab? | a dry cell |
| What do we call a large discharge of static electricity from cloud to cloud or cloud to ground? | Lightning |
| What happens to clouds in a thunderstorm? | Circulating winds cause a build up of negative charges near the bottom of the cloud by conduction (rubbing of molecules/atoms within the cloud) |
| What happens to the ground and objects on the ground in a thunderstorm? | As charged clouds draw closer, negative charges move away from them, giving the surface of the ground/objects a positive charge (charging by induction) |
| What is lightning? | A large discharge of static electricity from cloud to cloud or cloud to ground caused when negative charges “jump the gap” to a positively charged area. |
| What do we call it when static electricity or other unwanted charges are directed into the earth through a conductor? | Grounding |
| What causes thunder? | The superheating of air during a electric discharge (lightning) causes it to rapidly expand, producing sound waves (thunder). |
| What is the SI unit for measuring current? | Amps |
| A closed loop that electric current flows through is a ______ | circuit |
| A circuit with only one path (loop) for current to flow through is a ________. | Series circuit |
| A circuit with more than one path for current to flow through (each device has its own path) is called a _____. | Parallel circuit |
| What is one example of a series circuit? | Older Christmas lights (when one bulb goes out, the whole string won't light) |
| How are most houses wired today? | They are wired in parallel. |
| Name some household safety devices. | Fuses, circuit breakers, grounded outlets, GFCI outlets |
| What does a closed circuit require for current to flow? | A Voltage difference |
| The difference in potential electric energy, or charge, between two areas that creates the push to move charges in a circuit. | voltage |
| In SI, what is the unit for Voltage? | Volt |
| This produces a voltage difference when a chemical reaction makes the carbon suspension rod positive, and the zinc container negative | Dry Cell |
| The voltage difference in this is created by a chemical reaction in an electrolyte solution | Wet Cell |
| What creates the voltage difference found in wall outlets? | The generator at a power plant provides the "push" that we use to run electric appliances |
| Opposition to the flow of current in a circuit is called ______. | Resistance |
| What is the SI unit for resistance? | Ohms. (The ohm symbol resembles an upside-down horseshoe) |
| What does resistance tend to produce? | Heat and/or light |
| What are the three parts of a circuit? | 1) a voltage source, 2) a path for current 3) a device that uses light and provides resistance |
| What is the difference between AC & DC? | DC (direct current) flows in one direction; AC (alternating current) switches directions many times per sec. |
| What have we studied that uses direct current? | A flashlight (powered by a battery or solar cell) |
| What type of current is found in our homes? | Alternating current |
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judi829
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