P2: electricity Flashcards

1
Q

Define electricity

A

The motion of charged particles

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2
Q

How does an object become charged?

A

For something to become charged it has to gain or loose electrons

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3
Q

Why do charge objects attract or repel?

A

Charged objects attract or repel because they create electric fields around themselves

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4
Q

How is lightning made?(4):

A
  • clouds become negatively charged due to friction from hail.
  • this repels electrons on the ground, revealing the protons
  • electrons try to move to the ground, those who have create a path for other electrons
  • this creates heat and light,which is lightning
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5
Q

What fuels a circuit?

A

The fuel in a circuit is the battery/cell , the ENERGY it provides is measured in JOULES

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6
Q

charge(3):

A

Measured in coulombs (c)
Charge= current(a) x time(s)
(Q=I X T )

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7
Q

Define potential difference

A

The energy transferred per unit charge

PD= energy(j)/charge(c)

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8
Q

Define current

A

The speed at which they move around, measured in AMPS (A)

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9
Q

Define resistance(2):

A
  • The measure of how much the current is slowed down by components in a circuit
  • Resistance(Ω)= current (a) / potential difference (v)
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10
Q

Electricity is …

A

Always trying to find the fastest route to the ground

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11
Q

What is ohms law?

A

Ohm’s law states that the current through a conductor is directly proportional to the voltage across two points.

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12
Q

Overhead and under ground cables(6):

A
Overhead:
\+ easier to fix + does not require a cooling system + could fall - ugly
Underground :
\+ electricity won’t shock anyone 
- requires cooling system (expensive)
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13
Q

Series circuits(2):

A
  • CURRENT IS THE SAME

- POTENTIAL DIFFERENCE IS SHARED

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14
Q

Parallel circuits(2):

A
  • CURRENT IS SHARED

- POTENTIAL DIFFERENCE IS THE SAME

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15
Q

What is the purpose of the fuse?

A

If for any reason the voltage gets too high the thin wire in the fuse will snap and melt, cutting the circuit

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16
Q

What is the mains electricity?

A

230V

17
Q

What is the equation of power?

A
Power= voltage x current 
P= V X I 
Power= (current)^2 x resistance
P= I ^2 x R
Power = Work done / time 
P= W/t
18
Q

The national grid(5):

A

Power station-step up transformer-pylons and cables-step down transformer-house

19
Q

Power:

A

P= energy(j)/time(s)

20
Q

Direct current:

A

Flow of electric charge in only one direction

21
Q

Alternating current:

A

Electric current continually changes direction

22
Q

Live wire(2):

A
  • Brown

- Conducting wire connection that carries the alternating current

23
Q

Neutral wire(3):

A
  • Blue
  • Conducting wire connection that allows electrical charge to its return source
  • Completes the circuit
24
Q

The National Grid (definition):

A

A network of cables and transformers that links power stations to consumers across the country

25
Q

Why are the outer castings of plugs made from plastic?

A

This is because plastic is an insulator and does not conduct electricity

26
Q

Step-up transformers:

A

Transformers that changes an alternating potential difference across the primary coil to a higher potential difference across the secondary coil

27
Q

Step-down transformers:

A

Transformers that changes an alternating potential difference across the primary coil to a lower potential difference across the secondary coil

28
Q

Ammeters are connected in…

A

Series

29
Q

Voltmeters are connected in…

A

Parallel

30
Q

In any Ohmic resistor the resistance…

A

stays constant

31
Q

Current flows from the…

A

positive end to the negative end of the battery

32
Q

The current and potential difference alternates between…(2)

A

The live wire and the neutral wire

33
Q

The earth wire(3):

A
  • It is named as such because it is connected to the earth
  • Current will pass through the earth wire if there is a fault
  • It is a safety wire to stop appliances becoming live
34
Q

Why are the pins in a plug made of brass?(2)

A
  • Conducts electricity

- Does not oxidize

35
Q

Why is copper used in wires?(3)

A
  • Ductile
  • Bends easily
  • Conducts electricity
36
Q

Van Der Graff machine:(4)

A
  • The band moves in the machine which creates friction
  • This makes the dome negatively charged
  • This also makes the person touching the dome negatively charged
  • The hair separates as it is all negatively charged and so they repel
37
Q

What do the letters AC stand for?

A

Alternating current

38
Q

What happens to the resistance of the temperature increases?

A

It increases because of the increased movement of particles obstructing the current

39
Q

Electricity is transferred across a step-up transformers to…

A

Increase the potential difference from power stations