P4 - Electric Circuits Flashcards
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Switch open and closed Cell Battery Diode Resistor Variable resistor LED Lamp Fuse Voltmeter Ammeter Thermistor LDR
What is electrical current
The flow of electrical charge. The size of the current is the rate of flow
Equation linking charge flow and current?
Charge flow = current x time
Equation linking potential difference and current
Potential difference = Current x Resistance
V = I x R
What is the rule for current through a resistor?
The current through an ohmic conductor (at constant temp)is directly proportional to the potential difference across the resistor. This means that the resistance remains constant as the current change
Rule for the current and potential difference through a lamp
The resistance of a filament lamp increases as the temperature of the filament increases
Link between potential difference and current in a diode?
The current through a diode flows in 1 direction only with very high resistance in the reverse direction
What is a thermistor and it’s use?
The resistance of a thermistor decreases as the temperature increases
Use- in circuits in a thermostat
What is an LDR (light dependant resistor) and it’s use?
The resistance of an LDR decreases as light intensity increases
Use - in circuits switching lights on when it gets dark
What are the rules for a series circuit
- Current is the same everywhere
- Potential difference is shared between components. P.D of all components add to the P.D of the source
- Resistance shared aswell
What are the rules for a parallel circuit?
- Potential difference across each component is the same
- The total current through the whole circuit is the sum of the currents through the separate components
- The total resistance of 2 resistors is less than the resistance of the smallest individual resistor
