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9 Cards in this Set
- Front
- Back
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What does a diode do?
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Only allow current in one direction. A light-emitting diode (LED) lights up when current passes through it.
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What is electric current?
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The flow of charge. When a torch is one, millions of electrons pass through the torch bulb and through the cell every second.
The size of an electric current is the rate of flow of electric charge. This is the flow of charge per second. The more electrons that pass through a component, the bigger the current passing through it. It is measured in amperes (A). |
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What is electric charge measured in?
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coulombs (C).
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What is potential difference?
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The energy transferred to a part of the circuit or the work done on it by each coulomb of charge that passes through it. The unit is the volt (V).
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What is resistance?
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Electrons passing through a torch bulb must pass their way through lots of vibrating ions in the metal filament. The ions resist the passage of electrons through the torch bulbs. The unit is the ohm (Ω).
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What is Ohm's law?
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The current through a resistor at constant temperature is directly proportional to the potential difference across the resistor.
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What is the current-potential difference graph for a filament bulb and a diode?
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For a filament bulb the line curves towards the potential difference axis. The current is not proportional to the potential difference so it as a non-ohmic conductor. The resistance increases as the filament temperature increases since the ions in the metal filament vibrate more so they resist the passage of electrons more.
The diode curves towards the current axis in the forward direction, but the current is virtually zero in the backwards direction. The diodes resistance in the reverse direction is higher than in the forward direction. A diode is a non-ohmic conductor. |
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What is the current, potential difference, and resistance like in a series circuit.
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In a series circuit, the same current passes through each component.
In a series circuit, the total potential difference of the voltage supply is shared between the components. The total potential difference of cells in a series is the sum of the potential difference of each cell. The total resistance of components in a series is equal to the sum of the resistance in each component. |
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What is the current, potential difference, and resistance like in a parallel circuit?
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The total current through the whole circuit is the sum of the currents through the separate components.
For components in parallel, the potential difference across each component is the same. The bigger the resistance of the component, the smaller the current through it. |
