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electricity Flashcards

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1
Q

resistor versus fixed resistor

A

A resistor restricts or limits the flow of electrical current, fixed resistor has a resistance that does not change

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2
Q

What is a variable resistor?

A

moving the position of the slider on the resistor changes the resistance

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3
Q

What is a thermistor?

A

Its resistance depends on temperature. Low temperatures, it has a high resistance and vice versa

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4
Q

what is a light dependent resistor

A

Its resistance depends on light intensity. At lowlight levels, it has a high resistance and vice versa.

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5
Q

what is a semiconductor diode?

A

It allows current to flow in One Direction only

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6
Q

what are the two types of current?

A

Directing an alternating

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7
Q

What is charge measured in?

A

coulombs

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8
Q

what is the equation for the charge passing a point in a circuit?

A

Charge = current x time

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9
Q

What is current measured in?

A

Amps

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10
Q

What is potential difference?

A

The difference in the amount of energy that charge carriers have between two points of the circuit

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11
Q

what is potential difference measured in?

A

Volts

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12
Q

What is the equation for potential difference?

A

Energy/charge

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13
Q

what is energy measured in?

A

joules

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14
Q

what is ohms law?

A

voltage = current x resistance
v = i r

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15
Q

It’s a series circuit with one loop or multiple loops

A

One loop

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16
Q

what will ammeters read in a series circuit?

A

The same current

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17
Q

Properties of a series circuit

A

Current is the same through each component, the total potential difference of the power supply is shared between the components, and the total resistance of the circuit is the sum of the individual resistors

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18
Q

Factors of parallel circuits

A

The total current supplied is split between the components on different loops, potential difference is the same across each loop, the total resistance of the circuit is reduced as the current can flow multiple paths

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19
Q

What makes a wire hot?

A

Electrons collide with ions in the wires, and the ions vibrate more which heats up

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20
Q

What’s the equation for the amount of energy transferred each second between the energy stores?

A

Power= current x potential difference

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21
Q

One watt =

A

One joule /s

22
Q

what are the two ways power can be written

A

Current x potential difference
Current^2 x resistance

23
Q

what is resistance measured in

A

ohms

24
Q

what does a direct current look like on a voltage time graph

A

A straight horizontal line at a constant voltage

25
Q

What are some examples of a DC charge?

A

Call batteries, dry cells and solar cells

26
Q

what would an alternating current look like on a voltage time graph?

A

A curve alternating between positive and negative voltages

27
Q

components in a plug

A

Earth, wire, neutral wire, live wire, fuse, cable grip, and outer insulation

28
Q

Function of outer insulation

A

all three wires, are bundle together for safety

29
Q

function of cable grip

A

How old is the cable tightly in places So wires do not become loose

30
Q

Function of live wire

A

A copper wire coated with brown plastic along which the current enters the device

31
Q

function for the fuse

A

A glass or ceramic canisters containing a thin wire that melts if the current gets too high

32
Q

Function of the neutral wire

A

copper wire coated with blue plastic, that also connects to the cable in the wall and completes the circuit

33
Q

Function of earth wire

A

Copper wire coated in striped plastic that provides a path for current to flow from the case of the device to the ground, if there is a fault

34
Q

what would happen without the Earth wire?

A

There is a danger that the live wire wool touched the case and someone will get electrocuted

35
Q

What is the equation for the energy transferred by an appliance?

A

Energy= power x time

36
Q

What is power measured in?

A

watts

37
Q

what is a potential difference of mains electricity?

A

230v

38
Q

what are the five stages in the National Grid?

A

Power station, step up transformers, high-voltage transmission lines, step down transformers, consumers

39
Q

what are the transformers used for

A

To change voltages and currents in transmission lines

40
Q

how can you determine whether a transformer is a step up or step down?

A

The number of coils

41
Q

As power transferred stays the same, what happens as the voltage increases on the National Grid?

A

Current decreases and vice versa

42
Q

what does the step up transformer increase the voltage to?

A

25,000 votes to 400,000 votes

43
Q

What is the frequency of mains electricity?

A

50 hertz

44
Q

What colour is the live wire?

A

Brown

45
Q

which wire contains the fuse?

A

Live wire

46
Q

Describe the Earth wire

A

provides a low resistance path to the ground

47
Q

What does a step down transformer do?

A

increases the current and lowers voltage

48
Q

Electric current created chemically is always…

A

Direct

49
Q

what happens when two insulating materials are rubbed together?

A

Electrons will transfer from one to the other, leaving one positively charged and one negatively charged

50
Q

How are electric fields drawn?

A

Lines stick out perpendicularly from surface, arrows from positive to negative.
Closer together lines equals stronger field

51
Q

Why do sparks occur?

A

Potential difference between the object and the earth increases, causing electrons to jump between

physics (2 decks)

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