Electricity Flashcards
(14 cards)
What causes current to flow?
For an electric charge to flow through a closed circuit, the circuit must include a source of potential difference (voltage).
What is the value of the current at different points in a closed loop?
The current is the same everywhere in a single closed loop.
What does the current of a circuit depend on?
The current in a circuit depends on the resistance and potential difference of a component. The greater the resistance the lower the current of the component.
How is current related to potential difference across an ohmic conductor?
The current through an ohmic conductor is directly proportional to the potential difference across the resistor. The resistance remains constant
What happens to the resistance of a filament lamp as the temperature changes?
As the temperature increases so does the resistance of the filament lamp.
What does a diode do?
A diode makes it so that current flows in only one direction as it has a very high resistance in the opposite direction.
What happens to the resistance of a thermistor as temperature increases?
As the temperature increases the resistance of the thermistor decreases. This can be used in fridges to keep the temp. low.
How does the resistance of an LDR change?
As the light intensity increases, the resistance of an LDR decreases. This can be used on automatically brightness changing phones.
How can you use a circuit to find the resistance of a component?
Build a circuit with an ammeter in circuit and then place a voltmeter parallel to the circuit and then do R = Voltage/Current.
What are the rules for current, potential difference and resistance in a series circuit?
The current is the same across all components, the total potential difference is shared across all components and the total resistance is the sum of the resistance of each component.
What are the rules for current, potential difference and resistance in a parallel circuit?
The total current is the sum of the current through each branch, the potential difference is the same across each component and the total resistance of two resistors is less than the resistance of the smallest individual resistor.
What is the difference between AC (alternating current) and DC (direct current)?
Alternating current switches directions periodically whilst direct current always travels in the same direction.
What is the potential difference and frequency of electricity in the UK?
230 Volts and 50 Hertz
