# Electricity

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- Created by: moryriller
- Created on: 10-11-15 20:50

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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## Other cards in this set

### 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

### Card 4

#### Front

The other object, subsequently, becomes...

#### Back

### Card 5

#### Front

Therefore, the two objects...

#### Back

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