Physics - Electricity
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- Created by: twilkinson
- Created on: 04-06-17 14:53
What does each circuit symbol stand for?
Photocopy from book
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What mus there be in order for charge to flow?
A full connected circuit and a source of potential differance
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What is current?
Flow of electrical charge
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What is the equation linking charge flow, current and time?
Charge flow (C) = current (A) X Time (S)
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In what circuit will current be the same in all places?
Single loop circuit (series)
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What does the current through a component depend on?
The resistance of the component and the potential difference across the component
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What happen if you increase the resistance of a component?
The current decreases
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What is the equation that links potential difference (V), current (A) and resistance ( )
Potential difference (V) = current (A) X resistance ( )
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The current through an ohmic conductor (at a constant temperature is directly proportional to what?
The potential difference across the resistor. This means as the current changes resistance remains constant
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What happen if you increase the temperature of a filament lamp?
The resistance increases
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What happen if you increase the temperature of a thermistor?
The resistance decreases
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What happens to an LDR as you increase the light intensity?
The resistance decreases
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What happens to the current in a diode?
It only flows in one direction and has a very high resistance in the other direction
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Where are thermistors used in everyday life?
They can be used in green houses to monitor temperature, in fridges and in homes
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What are LDRs used for?
Automatic lights, car headlights, street lamps
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What does a series circuit look like?
photocopyyyyyyyy
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What does a parallel circuit look like?
Same boiiiiiiiii!
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What happens to the current in components connected in series?
It is the same a each one
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What happens to the potential difference of of the power supply when components are connected in series?
The potential difference is shared between the power components
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How doe you work out the total resistance of components in a series circuit?
Add the resistance of each component
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What happens to the potential difference over components joined in a parallel circuit?
It is the same at each component
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What is the total current of the whole of a parallel circuit?
The sum of the current running through every component
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What is the difference between series and parallel circuits?
In a series circuit, if one component breaks and has no current running through, then the other components will not work, but in a parallel circuit if one component does not work the others will still work.
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Why does adding resistor in series add to the overall resistance of the circuit?
Because the resistance of a series circuit is the some of the resistance of every component
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Why does adding a resistor in a parallel circuit decrease the total resistance?
Adding more resistors in parallel is equivalent to providing more branches through which charge can flow, lowering the resistance
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What is direct current?
current that flow in one direction around the circuit. This is battery powered
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What is alternating current?
Current that flows backwards and forwards around the circuit. This is mains electricy
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What is the voltage of direct current?
1.5 V
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What is the voltage and frequency of alternating current?
230 V, 50 Hz
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What is the difference between direct and alternating potential difference?
The potential difference of alternating current varies between a large positive number and a large negative number, whereas the potential difference of direct current is constant
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How are most electrical appliances connected?
Using a three pin plug
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Which insulating cover colour codes which wire?
Brown = live wire, blue = neutral wire, green and yellow wire = earth
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What does the live wire carry?
The alternating potential difference from the supply?
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What does the neutral wire do?
Completes the circuit
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What does the earth wire do?
Earth wire is a safety wire to stop the appliance from becomming live
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What is the voltage of the Earth wire?
0 V, it only carries a current if there is a fault
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What are the dangers of a connection between the live wire and the earth wire?
If a live wire connects with any other part of the appliance it can charge it, causing the next person to touch it to get a shock
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What is the equation that links power, current and potential difference?
Power (W) = Potential difference (V) X current (A)
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What is the equation that links power, current and resistance?
Power (W) = current (A) X resistance ( )
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What does the amount of energy an appliance transfers depend on?
How long the appliance is on for and the power of the appliance
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What is work done?
When charge flows in the cicuit
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What equation links energy transferred, power and time?
Energy transferred (J) = power (W) X time (S)
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What equation links energy transferred, charge flow and potential difference?
Energy transferred (J) = charge (C) X potential difference (V)
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What is the national grid?
A system of cables and transformers linking power stations to consumers
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What does a step up transformer do?
increases the potential difference to get the energy from the power station to the consumer
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What does a step down transformer do?
Lowers the potential difference for domestic use of the energy
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Why is the national grid an efficient way to transfer energy?
Because the high voltage means that a lot less energy is lost as heat during the journey
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What happens when certain insulating material are rubbed together?
They become charged. Negative electrons from one of the materials are rubbed off onto the other, and one becomes negatively charged and the other becomes equally positively charged
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What happens when two electrically charged items are brought near one another?
They exert a force onto one another. Two objects with the same force attract and two forces with opposite forces repel
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What are attraction and repulsion of these forces an example of?
Non-contact force
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What does a charged object create around itself?
An electric field close to the charged object
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What happens when you move two object with the same force closer together?
The force of repulsion gets stronger
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What is an electric field?
a region around a charged particle or object within which a force would be exerted on other charged particles or objects.
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Other cards in this set
Card 2
Front
What mus there be in order for charge to flow?
Back
A full connected circuit and a source of potential differance
Card 3
Front
What is current?
Back
Card 4
Front
What is the equation linking charge flow, current and time?
Back
Card 5
Front
In what circuit will current be the same in all places?
Back
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