Electricity

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What is static electricity?
Electricity generated due to friction and an opposite of charges between 2 objects
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Give 3 uses of static electricity
Pollution control, painting cars, defibrillators
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How does a balloon become charged?
As it is an insulator, when it is rubbed with another object, electrons are transferred to the balloon, giving it a negative charge
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The other object, subsequently, becomes...
... positively charged
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Therefore, the two objects...
... are attracted to each other
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Why would hair, for example, separate out into individual strands when charged?
Because the protons are attracted to the balloon, so the protons repel each other
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Current flows from ....
... negative to positive
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This is because there is a ...
... potential difference
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What is electric current?
The flow of charge
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What is the symbol for electric current?
Amp (I)
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What is the symbol for the flow of charge?
Coulombs (C or Q)
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How do you calculate current if you know the Coulombs and time?
Current = Charge (s) / Time (s)
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What is the charge if the current is 7A and the time for which it is on is 1 minute and 20 seconds?
Charge = Current x Time = 7 x 80 = 560 Coulombs
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How do you calculate voltage from the power and current?
V = P / I
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What is the Power if the kettle is connected to the mains, the charge is 720C and the time for which it is used is 1 minute?
1) Calculate the current: I = Q/T = 720/60 = 12A; 2) P = IV = 12 x 230 (Mains) = 2760W or 2.67kW
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What is Ohm's Law?
V = IR or Voltage (V) = Current (A) x Resistance (Ohms)
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What is the Resistance if the current is 13A and the Voltage is off the mains?
R= V/I = 230/13 = 17.7 A
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The size of the electric current is the...
... rate of flow of electric charge. This is the flow of charge per second.
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An electric current of 1 A is a rate of flow of charge of ...
...1 Coulomb per second (1C / 1s = 1A)
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What is the purpose of a diode?
Allows current through in only 1 direction
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What does a Variable Resistor do?
Varies the current of the circuit and thus varies the resistance
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What does an LED do?
Emits light when a current passes through
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What does a fuse do?
It is designed to melt and break if the current of the circuit is too high. It breaks the circuit and keeps us safe.
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A fuse is a...
... conductor
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What does a circuit breaker do?
A circuit breaker is a specially designed switch that automatically opens to interrupt circuit current in the event of an overcurrent condition.
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In a series circuit, the voltage is... and the current is... across all components
... divided...constant....
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In a parallel circuit, the voltage is.... and the current is... across al components
....constant...divided
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What is it known as when the current is constant over all components in a series circuit?
Kerchoff's Law
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Should an ammeter be connected in series or parallel? What about a voltmeter?
Ammeter: Series; Voltmeter: Parallel
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How do you calculate the voltage across an individual component?
Voltage = Work Done (or Energy Transferred) / Charge in Coulombs
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Find the total resistance of 2 resistors with values of 3 Ohms and 9 Ohms
Total resistance = 1/3 + 1/9 = 3/9 + 1/9 = 4/9. Flip the fraction: 9/4 = 2.25 Ohms
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What does the graph for a Filament bulb look like?
An elongated 'S', going through point (0,0) diagonally
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What does the graph for a Diode look like?
Goes along point (0,0) until 0.6V and then shoots up. Does the same with the negative Voltage (but goes down rather than up)
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Do the graphs for a Diode and Filament Bulbs follow Ohm's Law?
No; they're not directly proportional
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Does the Mains voltage use AC or DC?
AC
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What does every mains circuit have?
A live wire (brown), neutral wire (blue), and an earth wire (green and yellow)
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Why do we have a green and yellow wire?
So that, if the circuit breaks, the current will flow back to the supplier rather than to you and, thus, stop the current flowing through you.
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What is the other name for the amplitude of an AC wave?
Peak Voltage
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What is the other name for the wavelength of an AC wave?
Time Period
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How do you calculate the frequency of an AC wave?
Frequency (Hz) = 1 / Time period
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How do you calculate the energy transferred of a circuit?
Energy Transferred = Power x Time
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What is the power when the Energy Transferred is 360J on for 2 minutes?
Power = Energy Transferred / Time = 360 / 120 = 3W
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What is the Voltage when the Resistance is 3 Ohms, the energy transferred is 5760J, the power is 120W and the charge is 600C?
1) Calculate the time for which it acts: time = Energy transferred / power = 5760/120 = 48 seconds. 2) Calculate current = I =Q/t = 600 / 48 = 12.5A. 3) V = IR = 12.5 X 3 = 37.5 V
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Card 2

Front

Give 3 uses of static electricity

Back

Pollution control, painting cars, defibrillators

Card 3

Front

How does a balloon become charged?

Back

Preview of the front of card 3

Card 4

Front

The other object, subsequently, becomes...

Back

Preview of the front of card 4

Card 5

Front

Therefore, the two objects...

Back

Preview of the front of card 5
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Comments

samiraabby

shocking :(

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