P2- Electricity Flashcards
What is current?
Current is the flow of electrical charge.
What needs to be present for the electrical charge to flow?
The circuit needs to be closed.
There needs to be a source of potential difference.
What is another term for potential difference?
Voltage
What is the unit of current?
Ampere/ amps
In a series circuit, is the current the same of different around the circuit?
The current has the same value everywhere.
What is potential difference/ Voltage?
The driving force that pushes the charge around.
What is the unit of potential difference?
Volts/ V
What is resistance?
Anything that slows the flow down, decreases the current.
What is the unit for resistance?
Ohms Ω
What does the current flowing through a component depend on?
The potential difference across it and the resistance of the component.
What does a greater resistance across a component mean for the current?
The smaller the current that flows ( for a potential difference across the component.)
What does the total charge of a circuit depend on?
Current and time.
What is the equation for charge flow?
Charge flow= Current* time
Q= It
Q= Charge flow/ coulombs, (C) I= Current (A) t= Time (s)
What is charge measured in?
Coulombs, C
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Cell
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Battery
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Switch open
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Switch closed
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Filament lamp (bulb)
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Fuse
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LED
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Resistor
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Variable Resistor
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Ammeter
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Voltmeter
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Diode
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LDR
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Thermistor
What is the equation for power?
Power= Voltage * current P= VI
What is the equation for work done?
Work done= power* time
E= Pt
What is the equation for energy transferred?
Energy transferred= Charge flow* voltage
E=QV
What is the equation for Voltage?
Voltage= Current * Resistance
V=IR
What is the brown wire called?
What does it do?
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Live Wire
Provides alternating potential difference
-230v to 230v
What is the green and yellow wire?
Earth Wire
It stops the appliance from becoming live.
It doesn’t carry current.
Its at 0V
What is the blue wire?
What does it do?
Neutral Wire
Completes the circuit.
Takes the current out and away.
0V
UK mains supply, what type and how many volts?
Alternating current (ac) 230V
What are the two types of electricity supplies?
Explain each
Alternating current (ac) Direct current (dc)
(ac supplies) Current constantly changes direction produced by alternating voltages of positive and negative ends, at 50Hz.
Hz= cycles per second
Direct current= A current that is always flowing in the same
direction. Its created by a direct voltage.
What components supply direct current?
Batteries and cells.
What is the national grid?
It’s a giant system of cables and transformers that covers the UK and connects power stations to consumers (anyone using electricity)
The national grid transfers electrical power from power stations anywhere on the grid (the supply) to anywhere else on the grid where its needed (the demand) eg homes and industry.
What does the Ammeter measure?
Where must it always be places (series)
The ammeter measure the current (in amps) flowing through the test wire.
It must always be placed in series with whatever you’re investigating.
What does the voltmeter measure?
Where must it be placed?
The voltmeter measures the potential difference (pd) across the test wire (in volts.)
It must always be places in parallel around whatever you’re investigating. Not around any other bit of the circuit, e.g. the battery.
What resistance do Ohmic conductors have?
Ohmic conductors have a constant resistance.
With Ohmic conductors, what is the relationship between current and voltage at a constant temperature?
The current flowing through an Ohmic conductor is directly proportional to the potential difference across it , so you get a straight line. Pic
