Electric Circuits Flashcards
learn the drawings of ciruict symbols
Learn them
What is a switch?
Used to turn a circuit on and off
What is a lamp?
Electrical current hearts a filament in a bulb that gives out light
What is a fixed resistor?
Limits the flow of electrical current
Has a resistance that doesn’t change
What is a variable resistor and what is it used in?
Moving slider changes resistance
Used in dimmer switches and volume controls
What is a thermistor and what is it used in?
Resistance of thermistor depends on temperature
Used in thermostats or heat activeated fire alarms
What is an ldr and what is it used in?
Resistance of ldr depends on light intensity
Used in sensor cameras or automatic light that come on in the dark
What is a semiconductor diode
Allows current to flow in one direction
Diodes are used to convert alternating current into a direct current
What is an alternating current?
The direction of electron flow continually reverses
What is a direct current?
Flow of electrons is consistent around the circuit
What are electrons?
Negatively charged particles that transfer energy through wires as electricity
What is a charge and what is it measured in?
Property of a body which experiences force in an electric field
Measured in coulombs (C)
How do we measure current?
Using an ammeter placed in series with the component
How do you measure potential difference in a component?
A voltmeter must be placed parallel with the component
What is potential difference measured in
Volts (V)
What is the method to investigate how the length of a wire affects its resistance?
1) Connect the parts of the circuit properly
2)Connect crocodile clips to the resistance wire 100 cm apart
3)Record reading on ammeter and voltmeter
4)Move clips closer until 90cm apart
5)Record new readings
6)Repeat steps until the length of wire is minimum 10cm
7)Use R=V/I to calculate resistance
What is the method to investigate the relationship between current and potential difference for a resistor, bulb and diode?
1)Connect circuit properly
2)Ensure power supply is zero at start
3)Record readings on voltmeter and ammteer
4)User variable resistor to alter potential difference
5)Record new reading on voltmeter and ammeter
6)Repeat steps 3to four increasing potential difference slightly
7)Reverse the power supply connections and repeat steps 2-6
8)Repeat the experiment but with a bulb
What is the relationship between potential difference and current in a fixed resistor?
They are directly proportional
This is called Ohms Law because the resistance of the resistor is fixed and does not change
It is an ohmic conductor
What is the relationship between potential difference and current in a lamp
Current does not increase as fast as potential difference
The more energy in the bulb the harder it is for current to flow
What happens to current in a series circuit
It’s the same through each component
How is resistance shared in parallel curcuits
If resistors are connected in parallel the supply current is divided between them
What happens to current in parallel circuits?
Current is split between components on different loops
What happens to amount of potential difference in parallel circuits?
It’s the same across each loop
What happens to resistance in parallel circuits ?
Reduced as it can follow multiple paths
What is the method to investigate resistor networks?
1)Set up the circuit with an ammeter, switch and resistor in a series and then a voltmeter parallel
2)Turn on the power supply and close the switch
3)Record the voltmeter and ammeter readings and calculate resistance with R=V/I
4)Change the resistor and repeat step 2 to find resistance of second resistor
5)Place 2 resistors series to the circuit
6)Record voltmeter and ammeter readings and determine resistance with R=V/I
7)Do it again with resistors in parallel
What causes wires in a battery to heat up?
As electrons flow through the wire they collide with the ions in the wire so the ions vibrate more
This increased vibration increases temperature of the wire
Energy has been transferred from the chemical store of the battery to the internal store of the wire
