Electricity - Paper 1 Flashcards
To revise the key points from the Electricity topic (paper 1)
Draw the circuit symbol for a lamp
an X in a circle

Draw the circuit symbol for a diode
An arrow head in a circle

Draw the circuit symbol for a resistor
A rectangular box

Draw the circuit symbol for a variable resistor
A rectangular box with a diagonal arrow

Draw the circuit symbol for an LED
Same as a diode with 2 arrows points away

Draw the circuit symbol for a fuse
A rectangular box with a horizontal one running through it

Draw the circuit symbol for a voltmeter
V in a circle

Draw the circuit symbol for an ammeter
A in a circle

Draw the circuit symbol for a thermistor
a rectangular box with a diagonal line through it

Draw the circuit symbol for an LDR
A rectangular box in a circular with 2 arrows pointing towards it

Define Current
Flow of charge (electrons) measured in amps (A)
State the equation that links charge, current and time.
Charge (C)= Current (A) x time (s)
Q = It
What are the units of charge
Coulombs (C)
What is the relationship between current and resistance?
They have an inverse relationship. As resistance increases, current decreases and vice versa
State the equation that links potential difference, current and resistance
Potential difference (V) = Current (A) x resistance (ohms)
V = IR
State the units of potential difference
Volts (V)
State the units of resistance
Ohms
State the relationship between the length of wire and its resistance.
As the length of the wire increases the resistance increases. They are directly proportional. If the lenght of wire doubles then the resistance will double.
As more resistors are added in series what happens to the total resistance.
Total resistance increases (Rt = R1 + R2 + …..) as the current has to flow through every resistor.
As more resistors are added in parallel what happens to the total resistance.
As more resistors are added in parallel then the total resistance decreases. This is because the electrons have more paths they can take back to the battery.
State ohms law
Current is directly proportional to potential difference at a constant temperature. This means resistance remains constant.
Do the following components obey ohms law:
resistor?
Lamp?
Diode?
Resistor - yes
Lamp - No
Diode - No
Sketch the I/V graph for a resistor
A straight line through the origin (current and potential difference are directly proportional - an ohmic conductor)

Sketch the I/V graph for a bulb
It starts off as a straight line through the origin but the the current levels offs so the graph curves. Non ohmic conductor as current is not proportional to potential difference






