Electricity Flashcards
Which side of the cell/battery is positive and which side is negative?
The longer side is positive and the shorter side is negative
What is Ohm’s law?
V = IR
What is the unit of charge?
Coulombs (C)
What is the circuit symbolf for a fixed resistor?
a rectangle
What is a property of voltage in a series circuit?
The voltage of the power source is shared across all the components
What is current measured in?
Amperes
How do you work out the resistance if given the current and voltage?
Resistance = Voltage / Current
What does the IV graph look like for a resistor?
A straight diagonal line
What is the circuit symbol for a diode?
a circle with a triangle and a vertical line
What is the circuit symbol for a fuse?
a rectangle with a line through it
What is the unit for Resistance?
Ohms
What is the connection between current and voltage in a circuit with a constant resistance?
The voltage is proportionately bigger than the current
Why does the IV graph for a diode look like it does?
Diodes only allow the current to flow in one direction, so almost no current can flow in the other direction due to the high resistance
What is the circuit symbol for an LED?
a circle with a triangle and a vertical line with 2 arrows pointing off to the top right
What 2 components take meausrement in the circuit?
Ammeters and Voltmeters
What are the 4 types or resistors?
Fixed, Variable, LDR, Thermistor
What is the circuit symbol for a LDR?
a rectangle with a circle around it with arrows pointing towards it from the top left
What 2 products can LDRs be used in?
Automatic night lamps, and Burgular alarms
What is a property of current in a series circuit?
It is the same everywhere in a circuit
How do you work out the total resistance of a series circuit?
Add up the resistance of each component
What is a property of voltage in parallel circuits?
It is the same in each loop
Which way does current actually flow?
Negative terminal to Positive terminal
What does the IV graph look like for a filament lamp?
curve towards the origin then curve away from the origin
What does the IV graph look like for a Diode?
curve upwards from the x axis just after the origin
What is the circuit symbol for a thermistor?
a rectangle with a small horizontal line which becomes diagonal and crosses the rectangle
How is the resistance affected by light in an LDR?
If the light intensity is high, the resistance is low, but if the light intensity is low, the resistance is high.
How does the resistance change which the temperature in a thermistor?
The higher the temperature, the lower the resistance and the lower the temperature, the higher the resistance
How do you show the repulsion of 2 positive particles as a diagram?
lines curves away from the 2 positive particles
What is ionisation of air?
When the air particles lose electrons and become postively charged
Why does the IV graph look like it does for a filament lamp?
As the filament heats up in the bulb, the resistance increases, which means that the graph flattens as there is a higher resistance
How are sparks able to travel between objects?
The ionised air can conduct electricity, so sparks can be seen to travel between objects
What is resistance?
Everything that resists or opposes the flow of electrons
Which way does conventional current flow?
Positive terminal to negative terminal
How do you work out the voltage if given the current and resistance?
Voltage = Current * Resistance
What is the circuit symbolf for a variable resistor?
rectangle with a diagonal arrow pointing top right across it
What is the main difference between series and parallel circuits?
There is only 1 loop in a series circuit, but there are multiple loops in a parallel circuit.
What is a disadvantage of a series cicuit?
If one component stops working or one part of the cicruit breaks, the whole cicuit will stop working
Why is a parallel circuit better than a series circuit?
If a component breaks, other components in other loops will still work