P5 - Electric Circuits

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What is static electricity?
Electricity that doesn't flow
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What charge do electrons have?
A negative charge
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Explain the effects of static electricity on hair
When you brush you hair the electrons get scraped off because the positive charges don't move. The alike positive charges repell each other so different strands of hair stick out.
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What is current?
The flow of electicity or electrons
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What is current measured in, and what is it measured by?
Amps, by a ammetter. This is placed in series in a cicuit
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What is a series circuit?
When all the components are in one loop.
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What is the pattern of current in a series circuit?
The current stays the same all the way around the circuit because there is no-where else for the electrons to go
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What way do electrons travel around a circuit?
From negative to positive
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What is the pattern of current in parallel?
In parallel, the electrons spread out in the different loops, so will spread out equally depending on the components in the diffreent circuits. The current in the loops always add up to the start and end current.
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What is a parallel circuit?
Whre the components are in more than one loop.
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What is voltage?
The energy that electrons transfer to the components.
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What is volatge also known as?
Potential Difference - the difference between the energy before and after the component
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What is the pattern of volatge in series?
The voltage is spread out between the different components because each electron has to travel through more than one component.
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What is the pattern of voltage in parallel?
In parallel the voltage is the same all the way around the circuit because each electron only goes through one component, so can give it all of its energy to that component.
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What is the unit for resistance?
ohms
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What is resistance in a electric circuit?
An attempt to stop the flow of electrons
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What is the calcualtion for resistance?
Resistance=volatge/current
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The higher the volage the..............the resistance
The higher the volatge the higher the resistance
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Is there more resistance when two resistors are inn series or parallel?
There would be more resisitance in series because each electron has to go through more than one resistor. In parallel each electron only goes through one resistors so there is less overall resistance.
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What is a variable resistor?
When the reisiatnce can change by varying the amount of wire the electrons have to travel through.
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How does a dimmer switch work?
In a dimmer switch there is a coil of wire,a nd when you turn it it determines how far the electron shave to travel through that coil of wire. the more wire it has to travel througgh the more resistance there will be
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What does LDR stand for?
Light Dependant Resistor
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When does the resistance fall in a LDR?
When there is bright light because if there is low resistance there is low voltage.
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If it is dark, does it means there is high reisiatnce or low resistance, why?
High resistance because there is a high volatage when it is dark
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Why is a thermistor used in air conditioning?
Because if it is hot, there will be high resistance, so a high volateg meaning the air conditioner can work
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Why is there a LDR in street lights?
Because if it is dark, then there will be high resistance, so a high voltage, so the light will turn on.
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Name 2 examples when a LDR is used
Street lights, fridge lights
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Give two examples when a Thermistor is used
Air conditioning, heating
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What is the equation to calculate power?
Power=volatgexcurrent
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What is work done, and how is it calculated?
teh amount of energy transferred in a certain amount of time. Work done=powerxtime
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What are the fingers for the left hand motor rule?
thumb=motion first=field second=current
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When the field is forwards and the current is right the movenet is.............
upwards
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What 3 things do you need to generate elecricity?
Copper coil, motion, current
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What does the movement of the magnetic field do?
Generate current
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What is a A.C current?
Alternating current - when the volateg and current change direction every half turn of the magnet
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What is a direct current?
A current that flows in just one direction
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Where would you find a dc current
In a battery
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What do tranformers do in a electric circuit?
They either increase or decrease the voltage
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Where do you find tranformers?
In the national grid
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In a step up tranformer, which coil has the most turns and why?
The secondary coil because this creates a higher resistance so there is a higher voltage
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What is the name of the process that transformers use to change the volatge.
Elelctromagnetic Induction
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A trasformer has 40 turns on the primary coil and 800 on the secondary coil. If the unput voltage is 1000v, find he outut volatge.
40/800=0.05, so, 1000/0.05 = 20 000 v
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Other cards in this set

Card 2

Front

What charge do electrons have?

Back

A negative charge

Card 3

Front

Explain the effects of static electricity on hair

Back

Preview of the front of card 3

Card 4

Front

What is current?

Back

Preview of the front of card 4

Card 5

Front

What is current measured in, and what is it measured by?

Back

Preview of the front of card 5
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