SP10 Electricity and Circuits Flashcards
What is the role of the cell?
Provides the circuit with a potential differece, ie: energy per unit of charge
What is the role of the switch?
Turns the circuit on/off
What is the role of the resistor?
Limits the flow of current
What is the difference between a fixed resistor and a variable resistor?
A fixed resistor has a resistance that cannot change, whereas a variable resistor has adjustable resistance
What is the role of the thermistor?
Resistance based on the temperature. As the temperature increases, the resistance decreases
What is the role of the light dependant resistor?
Resistance depends on light intensity. As light intensity increases, resistance decreases
What is the role of the motor?
A device that converts electrical energy to mechanical energy
What is the role of the diode?
Allows the current to flow in one direction only. Used to convert AC into DC
What is the role of the ammeter?
Used to measure the current in a circuit. Connected in series with the rest of the components
What is the role of the voltmeter?
Used to measure the potential difference of an electrical component. Connected in parallel to the relevant component
Describe the direction of current flow
From the positive terminal to the negative terminal of the power supply
Define potential difference?
The amount of energy per unit of charge passing through the terminals
What is 1V =?
1J/C
What is the equation used to calculate potential difference?
energy transferred (J)/charge moved (Q)
Define electric current?
The rate of flow charge
What is the equation used to calculate current?
charge/time
What is needed in a circuit for the current to flow?
- a source of potential difference
- the circuit is closed: there are no gaps in the circuit
Define series circuit
The current can only take one path
Define parallel circuit
There are several junctions that allow the circuits to take different routes
What is current in electrical wires?
The flow of electrons
What equation links potential difference, current and resistance?
V = IR
State the difference between the direction of electron flow and the direction of conventional current
conventional current: positive terminal to negative terminal
electron flow: negative to positive
What does a large resistance cause?
The greater the resistance, the harder it is for charge to flow through the component, therefore the current is smaller
What happens to current at a junction?
It is conserved, which means that the current flowing in a junction is the same as the current flowing out of it
Compare series and parallel circuits
Series:
- current flows through all components together
- cannot switch individual components on and off
- potential difference is shared across the whole circuit
- current is the same throughout the circuit
Parallel
- current flows through each component separately
- can switch off each component individually
- potential difference is the same across all the branches
- current is shared between each of the branches
How do we calculate total resistance in a series circuit?
Sum of each of the individual resistors