Unit 2- Electricity Flashcards
Equation for charge
Current x time
The greater resistance across a component….
The smaller the current that flows through it
What is potential difference
A potential difference of 1 volt tells us that 1 joule of energy is transferred for each coulomb of charge that is moving through the circuit
What is resistance
Anything in the circuit which slows the flow down
How is current split through a circuit in series
Current is the same everywhere
Potential difference equation
Current x resistance
How is ohmic conductor represented on a graph
Constant gradient (temp)
What does a filament lamp look like on a graph
Curved line, as temp increases so does resistance
What does diode look like on graph
Flat line across then a curve upwards, diode has very high resistance
What is a LDR (light dependant resistor)
Resistor that is dependant on intensity of light, in darkness the resistance is highest
What is a thermistor resistor
Temp dependant resistor, in hot condition resistance drops so much less energy needed for current to pass through thermistor. In cool conditions the resistance increases
Are voltmeters connected in parallel or series
Parallel
How is potential difference split up in series
Is shared between components, so potential difference will always add up to the source potential difference
How is current split up in parallel
Shared between branches , it will add up to total current leaving the cell
How is potential difference split up in parallel
Same across all components
What is frequency of mains supply
50 Hz
What type of current is mains supply
Alternating current
What type of current is battery supply
Direct current
What colour is the neutral wire and what does it do
Blue , completes the circuit (0v)
What colour is the live wire and what does it do.
Brown, provides alternating potential difference (230v) from mains supply, connected to the fuse
What is the potential difference of mains supply
230 v
What colour is earth wire and what does it do
Green and yellow, protecting the wiring and for safety (0v)
What wire will give you an electric shock
Live wire
Power equation
Potential difference x current
What changes the potential difference in the national grid
Transformer (step up) (step down)
What is an ohmic conductor
Resistor at a constant temp
What does the diode symbol look like
Play symbol
What does an LED symbol look like
Play symbol with arrows coming off it
What does electric charges cause
An electric field, the closer to the object you get, the stronger the field is
What is direct potential difference
Potential difference in one direction
What happens to potential difference across an LDR and current in an LDR
P.d= increases
Current= decreases
Disadvantages of generating electricity using nuclear power stations
Non renewable
Produce radioactive waste
Advantages of nuclear energy
Carbon free electricity, reliable energy source, high power output
Name one fuel used in nuclear power stations?
Uranium
How would carbon capture prevent build up of carbon dioxide in the atmosphere
Carbon dioxide would not be released and instead would be caught and stored in huge containers
Why will the driver become charged when driving
Clothes and seat will rub together and electrons will transfer from driver to seat
How does an object become charged
Insulating materials rub against each other, electrons will transfer on to the other object
What affects charge
Temperature, humidity
Why don’t insulators conduct electricity
Electrons cannot move through them
What can a build up of electrostatic charge cause
A speak which could trigger an explosion
What does the national grid consist of
Transformers and high voltage cables
What is the disadvantage of the power cables in the national grid
Energy is always lost in the cables due to the resistance of the wires
How can we reduce energy lost in the national grid
-building power stations closer to our homes
Why does the step up transformers increase the potential difference
Because then less energy is lost in the power cables when the potential difference is high
What does alternating current mean
The flow of electrons move in the forward and the reverse direction
What are wires in a plug made out of and why
Copper which is a good conductor of electricity
What is the potential difference of the earth
0 volts
If the case becomes live what will happen
A huge amount of current will flow to the earth, the fuse will then melt and shut off the current, this prevents anyone from getting an electric shock from the case
What is direct current
The current from a cell is only moving in one direction
Benefit of alternating current
Very easy to use a transformer to increase or decrease the potential difference
Which direction does current flow
From the negative end of the cell to the positive end
Which way do scientists draw the current and what do they call this
Draw it in the opposite direction (positive to negative) this is called conventional current
What is charge
The size of the electrical current is the rate of the flow of electrical charge
What is the x axis in a ohmic graph / diode/ filament / LED
Potential difference
What is the y axis on a ohmic / LED / diode / filament graph
Current
In an ohmic conductor graph what is one condition that would result in the graph being directly proportional
If the temperature is constant
Negative of a filament lamp
Not very efficient
What does filament mean
(Contains) a very thin wire
Key feature of a diode
Current flows in only one direction, the diode has very high resistance in the other direction
Why is there a flat line on the graph for a diode
Because there is no current in the reverse direction
Uses for diodes in a circuit
Useful for controlling the flow of current in circuits
Where can you find LEDs in real life
Flash on phone, led lightbulbs, led televisions
