Electricity 4.3 Elctric Circuits Flashcards
What is a series circuit?
A series circuit is an unbranched loop
where the same charge passes through all components,
so the current through each component is the same.
What is a parallel circuit?
A circuit in which the charge is split between branches.
Describe the current across a series circuit
The current is the same across all points in a series circuit.
Describe potential difference in a series circuit
Potential difference is split between components, according to the ratio of their resistances.
Describe current across a parallel circuit
The current is divided between the branches of the circuit.
Describe the potential difference across a parallel circuit
Each branch has a potential difference equal to the potential difference of the supply.
What is total resistance in a series circuit?
The sum of the resistances from each component.
What is the total resistance in a parallel circuit?
The total resistance is lower than that of the branch with the lowest resistance.
1/R = 1/R1 + 1/R2 + …
Why is it advantageous to connect lamps in parallel?
-voltage is the same in parallel (not divided)
-if one component breaks, current can still go through
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How do multiple power sources affect emf?
In series, the emfs of individual sources are added to give the total emf.
Emfs in parallel do not add.
What is a thermistor?
A resistor in which resistance decreases as temperature increases
What is an LDR?
A resistor in which resistance decreases as light intensity increases
e.g. used in automatic night lights
What is a sensing circuit?
When the resistance of a circuit is dependent on an environmental factor such as light or temperature, so therefore can be used to monitor environmental changes.
What can sensing circuits be used for?
Light sensitive switches (eg. lampposts, night lights) or thermostats etc.
What is a diode?
A component which only allows current to flow in one direction (as the resistance in the other direction is too high).
