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Physics > Electricty > Flashcards

Electricty Flashcards

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1
Q

What is the ability of a variable resistor? + 1 use - Electricity

A

A resistor which can alter its resistance

Used in light switch dimmers

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2
Q

What is the ability of a thermistor? + 1 use - Electricity

A

A resistor which depends on temperature. As temperature increases, resistance decreases
Can be used in heat activated fire alarms and thermostats

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3
Q

What is the ability of a diode? - Electricity

A

A diode only allows current to flow in one direction

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4
Q

What is the ability of an LDR? + 1 use - Electricity

A

As light intensity increases the resistance decreases. Can be used in automatic lights that turn on when dark

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5
Q

What is the difference between AC and DC? - Electricity

A

In AC, the flow of electrons constantly changes direction, whereas in DC the flow of electrons stays the same direction

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6
Q

What is the equation linking charge, current and time? - Electricity

A

Charge (Q) = Current (I) x Time (t)

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7
Q

What electrical component measures current? + should an ammeter be in series or parallel to measure a component? - Electricity

A

Ammeter, should be placed in series

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8
Q

What component measures voltage and how is it connected? - Electricity

A

A voltmeter, which is always connected across a component

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9
Q

What equation links voltage, energy and charge? - Electricity

A

Voltage (V) = Energy (J) / Charge (Q)

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10
Q

What equation links voltage, current and resistance? - Electricity

A

Voltage (V) = Current (I) x Resistance (Ohms)

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11
Q

What happens if a component is broken in a SERIES circuit? - Electricity

A

The whole circuit will cease to function

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12
Q

What is the rule concerning current in a SERIES circuit? - Electricity

A

The current is the same around the entirety of the circuit (I1 = I2 = I3)

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13
Q

What is the rule concerning voltage in a SERIES circuit? - Electricity

A

The voltage across components throughout the circuit will all add to the value of the voltage across the cell
(V1 + V2 = V (cell))

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14
Q

What is the rule concerning resistors in a SERIES circuit? - Electricity

A

As current must flow through all parts of the circuit, the resistance of all total resistors is added to find the total resistance (total R = R1 +R2)

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15
Q

What is the rule concerning current in a PARALLEL circuit? - Electricity

A

The current will split among the different pathways, indicated by ammeters in different areas of the circuit

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16
Q

What is the rule concerning voltage in a PARALLEL circuit? - Electricity

A

The voltage in a parallel circuit splits evenly between pathways, as the energy transferred by electrons is the same in any path

17
Q

What is the rule concerning resistance in a PARALLEL circuit? - Electricity

A

Resistance is reduced as electrons split between paths, and therefore do not have to go through 1 resistor

18
Q

How do wires in a circuit heat up? - Electricity

A

Electrons collide with the metal ions, causing more vibrations from the ions, meaning that the wire temp increases

19
Q

What is the equation linking power, current and potential difference? - Electricity

A

Power (W) = Current (I) x Voltage (V)

20
Q

What equation links power, current and resistance? (HINT - ^2) - Electricity

A

Power (W) = Current^2 (I) x Resistance (Ohms)

21
Q

What can affect charged objects through contact with other charged objects? - Electricity

A

Static electricity

22
Q

How can objects become electrically charged through friction? + what charge do these objects that gain electrons have? - STATIC Electricity

A

Electrons can be transferred by friction between objects, with the object gaining electrons becoming negatively charged

23
Q

What happens to mean the electrons can transfer from one object to another? - STATIC Electricity

A

By applying friction, the electrons gain energy, enough to leave their atom

24
Q

Why can a balloon stick to a wall? - STATIC Electricity

A

The balloon has gained electrons to become negatively charged and is attracted to the positively charged wall

25
Q

What does a Van de Graf generator do? - Electricity

A

A Van de Graaf removes electrons to produce a positive charge

26
Q

What are the characteristics of the UK Mains supply? (freq, voltage) - Electricity

A

The mains supply is generated at 50 Hz and delivered at 230V

27
Q

What are the colours of each cables in a plug? - Electricity

A

Earth wire - green + yellow
Live wire - brown
Neutral wire - blue

28
Q

Why is copper used in plug wires? (2 reasons) - Electricity

A

It’s very ductile

Very good conductor of electricity

29
Q

What is the function of a fuse? - Electricity

A

A fuse melts if the current flowing through it is too high. This means that the circuit will break

30
Q

What is the purpose of the earth wire? - Electricity

A

Provides a low resistance path to the ground, so if a fault were to occur in the plug, the current would flow to earth

31
Q

What is the equation for energy? - Electricity

A

Energy = Power x time

32
Q

What does a step-up transformer do? - Electricity

A

Increases the voltage and reduces the current, to around 400,000 V. Reducing current means less energy lost through heating wire

33
Q

What does a step-down transformer do? - Electricity

A

Reduces the voltage to 230 V so it is safe for use in homes

34
Q

What is the equation for power? (Using current + resistance) - Electricity

A

Power = current^2 x resistance

Physics (10 decks)

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