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41 Cards in this Set
- Front
- Back
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What measures the current in a circuit? |
An ammeter |
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What does a circuit need to work? |
A source, a load, and a conductor. If the switch is open, it will not work. |
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How does current work? |
The electrons repel and push each other across the circuit. |
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Current |
The amount of charge (electrons) passing a point at any given moment |
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What unit is current measured in? |
Amperes (A) |
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Potential difference |
The amount of energy per one coulomb of charge. |
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What is potential difference also known as? |
Voltage |
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Units for current, resistance, and volts? |
Current: A Resistance: _n_ Volts: V |
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Symbols for current, resistance, and volts? |
Current: I Resistance: R Volts: V |
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What moves through the wires of a circuit? |
Electrons |
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What is the source? |
Source of energy (ex. Battery) |
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What is the load? |
Turns energy into other forms of energy and slows down current (ex. Bulb, TV, calculator, computer, etc.) |
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What is the conductor? |
Wire where current flows |
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Ohm's law |
V=IR Voltage = Current × Resistance |
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Difference between a wet cell and a dry cell? |
Wet cells have liquid electrolytes, and dry cells have paste. |
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What makes a battery better? |
When it has a bigger potential difference. |
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What does an electrochemical cell need? |
An electrolyte, plastic insulator, positive and negative terminals, 2 different types of metal. |
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How does a light bulb work? |
The fillement wire, tungsten, and bulb are a resisting load. It slows the electron wires and electrons to steal energy. Then the electrons will turn into a different type of energy (ex. Heat, light) |
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Difference between static electricity and current electricity? |
Current electricity is the continuous flow of charge in a complete circuit. Static electricity is where the electricity is held in one place. |
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What measures resistance? |
An ohmmeter |
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Series circuit |
Has one path for electrons to flow |
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Parallel circuit |
More than one path for electrons to flow |
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In a series circuit, what has to add up or stay the same? |
Current: same Voltage: add up Total resistance: add up |
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In a parallel circuit, what has to add up and what has to stay the same? |
Current: add up Voltage: same Total resistance: ohm's law |
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Energy formula |
E = Pt Energy = Power × time |
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Power formula |
P = IV Power = Current × Voltage |
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Units for power and energy |
Watts (W) and Joules (J) |
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Formula for Kilowatt-hour |
kWh = kW × h |
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Power |
The rate of change of energy or how much energy is used per second |
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Energy |
Depends on power of an electrical device and how long it is used for |
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What are two factors determine the output energy of a battery? |
Voltage and amount of charge |
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Conventional current |
Where electrons go from positive terminal to the negative |
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Electron flow |
Electrons go from the negative to the positive terminal |
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How do two conductors have a different current flow when they are travelling at the same speed? |
The area of one of them could be bigger or there is more electron flow. |
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Different types of energy sources |
Friction, piezoelectric crystals, photo - electrochemical cells, thermocouples, generators |
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What does the amount of electric force depend on? |
The distance separating the objects, type of charge, or the amount of charge on each object. |
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Laws of static charge |
- like charges repel - opposites attract - neutral objects are attracted to charged objects |
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Piezoelectric crystals |
When the crystal is squeezed, positive and negative charges are separated on the crystal and a small hammer hits the crystal, generating volts of electricity. |
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Photo - electrochemical cells |
Light hits the cell and some of the light energy breaks electrons off the surface of the cell. These separated electrons have the electrical energy to operate a calculator, etc. |
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Thermocouples |
Transforms heat energy into electrical energy. It is used in a kitchen oven |
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Generator |
When the wire or magnet moves close together, voltage is created |
