P2-Electricity Flashcards
What is current
The flow of electrical charge
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What is the ammeter
It measures the current flowing through the test wires
– the meter must always be placed in a series with whatever you’re investigating
What is a volt meter
Measures the potential difference across the test wire
– must always be placed in parallel around What ever you’re investigating
What is the relationship between current and resistance in an ohmic conductor
The current is directly proportional to the potential difference
What is the relationship between current and potential difference in a filament lamp
As the current increases the temperature of the filament increases , So the resistance increases
– this means that less current can flow per unit of potential difference
What is the relationship between current and potential difference in a diode
Current will only flow through diet One Direction however the diet has a very high resistance in the reverse direction
What is a light dependent resistor
There is it that is dependent on the intensity of light
– in bright light the resistance falls
– in darkness the resistance is highest
What is a thermistor
I thermostat is a temperature dependent resistor
– in hot conditions their resistance drops
– in cool conditions the resistance goes up
How is the potential difference distributed in a series circuit
The potential difference is shared between various components and therefore it always adds up
How is the current distributed in a series circuit
It is the same everywhere
– the size the current in each component is the same
How is the resistance distributed in a series circuit
Resistance adds up
How is potential difference distributed in a parallel circuit
Potential difference is the same across all components
– it’s equal
How is currently distributed in a parallel circuit
Current is shared between branches
– it adds up
What happens when you add a resistor in a parallel circuit
The total resistance decreases
–Because the potential difference is the same across all components and therefore by adding another loop the car in a small direction to go in and by increasing the current it needs a decrease in resistance
Happens when you add a resistor in a series circuit
The resistance increases
– this because by adding a resistor in series, but he resists have to share the potential difference
– the potential difference across a resistor is lower so the current through each resistor it’s also our
– in a series circuit the current is the same everywhere so the total current in the circuit is reduced when a resistor is added
-This means the total resistance of the circuit increases
What is DC
Direct current – it is a current that always flows in the same direction
What is AC
Alternating-current
– produced by alternating voltages which change direction
What is the colour of the live wire and what is its potential difference
- What does it do
Brown – 230
*It provides the alternating potential difference
What colour is the neutral wire ,what does it do And what is its potential difference
Blue – the neutral wire completes the circuit and carries away current
– it has a potential difference of 0 V
What colour is the Earth wire, what does it do and what is its potential difference
Green and yellow – it is used for protecting the wiring, and for safety – it stops appliance causing from becoming live
– It has a potential difference of 0V
Why can’t I live fire give you a potential shock
Your body is at 0 V – This means that if you touch the livewire a large potential difference is produced it across your body and a current flows through
– this causes a large electric shock
– your body provides a link between the supply of the Earth
– even if I plug socket or light switch is turned off there is still a danger and electric shock, I can’t as I’m flying with a still a potential difference in the live wire
Voltage is the UK mains supply
230 V
What is a power rating
They are labelled with the maximum safe power that they can operate at
-It was a toast to the maximum out of energy transferred between stores per second when applied is in use
What is the National Grid
Giant system of cables and Transformers that cover the UK and connect power stations to consumers
Why are step up stepdown transformers used
By having a high voltage and low current – less current means less energy is lost through heating to the wire
- It is therefore much cheaper
What is the function of step up and stepdown Transformers
The potential difference is increased and decreased for safe levels to the houses
