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Physics > Electricity > Flashcards

Electricity Flashcards

0
Q

Where is the neutral wire?

A

Bottom left

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1
Q

Where is the live wire?

A

Bottom right

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2
Q

What holds the cable in the plug?

A

Cable grip

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3
Q

Why are the metal parts made of copper or brass?

A

Good conductors

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4
Q

Appliances must be …………………..

A

Earthed or insulated

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5
Q

The live wire alternates between …………

A

High +ve and -ve voltage

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6
Q

What safety precautions should be taken using plugs to avoid hazards and electric shock?

A

Check for damage to plugs or insulating casing on mains operated devices.
Check cable isn’t frayed, damaged insulation can expose ‘live wires’
Check cables aren’t too long, or more likely to get damaged or trip people up.
No water around electric sockets or mains operated devices.
Never push metal in a socket - solved by using socket covers.

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7
Q

What does earthing or fuses do?

A

Prevent fires and electric shocks by blowing the fuse and cutting off the live supply.

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8
Q

What advantages do circuit breakers have?

A

They break the circuit by opening a switch
Can be easily reset no need to replace
Faster than a fuse

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9
Q

What is the equation for electrical power?

A

Power= Current x voltage

P = I x V

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10
Q

What is electrical power?

A

Rate at which an appliance transfers energy

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11
Q

What is the equation of energy transferred?

A

Energy transferred = Current x voltage x time

E = I x V x t

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12
Q

What are resistors?

A

An electrical current heats the resistor increasing the resistance so less current will flow
Fuses use this to protect circuits

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13
Q

What is current?

A

The rate of flow of charge round a circuit

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14
Q

What is voltage?

A

The driving force that pushes current and the energy transferred per unit charge passed.

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15
Q

How do you increase current?

A

Increase voltage

Decrease resistance

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16
Q

What is resistance?

A

Slows the flow down

17
Q

What is an ammeter?

A

Measures the current in amps.
Placed in a series circuit
Tells you how many coulombs of charge are passing through the lamps per second.

18
Q

What is a voltmeter?

A

Measure the voltage in volts
Place in a parallel circuit
Voltage, v1, across the lamp tells you how many joules of energy are being converted to heat and light per coulomb of charge passing through the lamp.
V1 + V2 = V.

19
Q

What is the difference between a.c and d.c supply?

A

Mains supply - a.c, constantly changing (alternating current)
Battery supply - d.c, (direct current)

20
Q

What is the equation for voltage?

A

Voltage = Current x resistance

V = I x R

21
Q

What does the I-v graph for a
Metal filament lamp
Wire
Diode

A

Lamp - curve graph
Wire - straight diagonal
Diode - in the x axis then straight up

22
Q

What are light emitting diodes used for?

A

Digital clocks
Remote controls
Traffic lights

23
Q

Describe a series circuit?

A

Everything on one line
Current same everywhere
Voltage is split

24
Q

Describe parallel circuits?

A

Branches
Same voltage
Split current

25
Q

What is the equation for charge?

A

Charge = Current x time

Q = I x t

26
Q

Voltage is the …………. Per ……………..

A

Energy transferred

Unit charge passed

27
Q

One volt is one joule per ………….

A

Coulomb

28
Q

What is static electricity caused by?

A

Friction

29
Q 
What are the units for the following:
Ampere
Coulomb
Joule
Ohm
Second
Volt
Watt
A 
Ampere, A
Coulomb, C
Joule, J
Ohm, ♎️
Second, s
Volt, V
Watt, W
30
Q

Understand the uses of insulation, double insulation, earthing, fuses, and circuit breakers.

A

Insulation - all mains wiring is double insulated, preventing separate conducts (live, neutral and earth) touching a ‘live’ (mains voltage) wire.

Double insulation - no chance of electric shock from casing.

Earthed - earth wire ensures outer casing is held at OV and provides low resistance path for current in the event of a fault.

Fuses - fitted in plugs and in consumer unit next to electricity meter. They are ceramic heat proof tubes that melt when the current size is exceeding and so cut off live supply, but need replacing.

Circuit breakers - do same job as fuses, breaking live connection. Operated magnetically and may be reset by pressing a button.

31
Q

What does a current in a resistor result in?

A

The electrical transfer of energy and an increase in temperature.

32
Q

What can lamps and LED’s be used for?

A

To indicate the presence of a current in a circuit.

33
Q

What is the equivalent of 1 volt?

A

1 volt = 1 joule per coulomb

34
Q

What is electric current in solid metallic conductors? (E.g. Copper, silver, gold - electricity conductors)

A

A flow of negatively charged electrons.

35
Q

What materials do not conduct electricity?

A 
Rubber
Glass
Plastic
Dry wood
(Usually non metallic)
36
Q

Unlike charges……

Like charges……

A

Unlike charges attract

Like charges repel

37
Q

How are positive and negative electrostatic charges produced on materials?

A

By the loss and gain of electrons.

38
Q

Describe an experiment to investigate how insulating materials can be charged by friction.

A

Rub a clear plastic ruler with a dry cloth.
Then hover the ruler over small pieces of dry paper, they will be attracted to the ruler.
Or you can place the rubbed ruler next to running water, the water should bend towards the ruler.

39
Q

Explain electrostatic phenomena.

A

In solids the positions of atoms are fixed and therefore the nuclei and protons within them are fixed, but the surrounding electrons can be made to move from place to place under certain conditions.

40
Q

Explain the potential dangers of electrostatic charges / static electricity.

A

Fuelling tankers - fuel flows out of filler pipe, static builds up, leads to a spark and in dusty, fumy places - boom! Solution - make nozzles out of metal so charge is conducted away instead of building up. Beneficial to have earthing straps between fuel and fuel pipe.

Lightning - rain drops and ice bump together in rain clouds, knocking off electrons, leaving top of cloud positively charged and bottom of cloud negatively charged. Creates huge voltage and bog spark.

41
Q

Explain some of the uses of electrostatic charges / static electricity.

A

Inkjet printers - charging ink droplets in inkjet printers allows droplets to be directed to places on paper by deflecting them between charged plates. They are attracted to plates with opposite charge to them.

Photocopiers - image plate is positively charged and an image of what you’re copying is projected onto it. Whiter parts of image make light fall on plate. Charged bits attract negatively charged black powder which is transferred onto positively charged paper. Paper is heated so powder sticks.

Physics (8 decks)

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