P4 Electric circuits Flashcards
What is static electricity?
When you rub two electrically insulating materials together and electrons are rubbed off one material and deposited on the other
What is a non-contact force?
A force between two charged objects
What is the equation for current?
Current (A) = Charge (C)/time (s)
What does a cell do?
Pushes electrons around a complete circuit
What does a switch do?
Enables current to be switched on and off
What does a bulb do?
Emits light when a current passes through it
What does a diode do?
Allows current through in one direction only
What does a light emitting diode do?
Emits light when a current passes through it
What does an ammeter do?
Used to measure electric current
What does a fixed resistor do?
Limits the current in a circuit
What does a variable resistor do?
Allows the current to be varied
What does a fuse do?
Designed to melt and “break” circuit if the current is greater than a certain amount
What does a heater do?
Transfers energy from an electric current to heat up surroundings
What does a voltmeter do?
Used to measure potential difference
How are voltmeters are always connected with the circuit?
In parallel
What is the equation for potential difference?
Potential difference (V) = Energy transferred (J)/Charge (C)
What is resistance?
The opposition to current flow
What is the equation for resistance?
Resistance (Ohms) = Potential difference (V)/Current (A)
What does Ohms law state?
That the current through a resistor at constant temperature is directly proportional to the potential difference across the resistor
Explain the relationship between the resistance and current of a filament lamp
As the resistance increases so does the current, because as the resistance increases so does the temperature
What is the relationship between resistance and temperature for a thermistor?
The resistance decreases if its temperature increases
What is the relationship between resistance and light intensity for a light-dependant resistor?
The resistance decreases as the light falling on it gets brighter
What would happen if there was a break at any point in a series circuit?
The charge would stop flowing
What is the current in each component in a series circuit?
The same
In a series circuit how is the total potential difference distributed?
It is shared between the components
How would you find the total resistance in a series circuit?
Adding the resistance of each component
What would happen to the resistance if you added more resistors to series circuit?
It would increase the total resistance because the current through the resistors is reduced and the total potential difference across them is unchanged
What would happen if there was a break in one of the branches in a parallel circuit?
Charge would still flow in the other parts
What is the total current in a parallel circuit?
It is the sum of the currents through separate components
What is the potential difference in a parallel circuit?
The same across each component
What would happen to the resistance if you added more resistors to parallel circuit?
The resistance would decrease because the total current through the resistors is increased and the total potential difference across them is unchanged
