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Physics GCSE > P5 > Flashcards

P5 Flashcards

1
Q

How are devices that use plugs and devices that use batteries different (Batteries use DC current)

A

-Battery devices can be used anywhere but plugged devices must be used near a plug
-Batteries transfer energy from chemical ptotential by electric current, plugs directly supply electrical energy

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2
Q

How aee devices that use plugs and devices that use batteries the same?c (plugges devices use AC CURRENT)

A
  • both transfer energy to electrical devices
  • both must be connected to the device
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3
Q

AC means

A

Alternating current

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4
Q

DC means

A

Direct current

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5
Q

Direct current means

A

The current flows in one direction only

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6
Q

Alternating current means

A

The current constantlg changes direction, how often is called frequency

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7
Q

DC examples

A

Cells, batteries

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8
Q

AC examples

A

Mains supply, power socket

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9
Q

DC current on a graph maintains a

A

Constant voltage due to the singke direction current flow

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10
Q

AC current on a graph constantly

A

Reverses its voltage (up and down) due to the current constsntly changing direction (freauency)(Hz)

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11
Q

Mains electricity

A

An alternating current

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12
Q

In the UK mains electricity is about

A

230 V

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13
Q

In the Uk mains electricity has a frequency of

A

50Hz

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14
Q

Transmitting electricity at a high voltage reduces power loss, making

A

The system more efficient

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15
Q

Step-up transformer

A

Increases the voltage, but decreases the current

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16
Q

Step- down transformer

A

Decreases the voltage, increases the current

17
Q

Power station function

A

Burns fuel - heats water - steam - turn turbine - turn generator - generate electricity

18
Q

Electricity is dustributed via the

A

National grid

19
Q

The national grid is a gaint susten if

A

Cables and transformers that civer the UK and connects power stations to consumers

20
Q

Disadvantages of underground cables

A
  • very expensive (miles and miles of cable)
  • lots of digging
  • maintenance is hard, must dig them up
  • cables get hot, hard too cool (underground). Must be thicker
  • would need to clearky mark where they are in order for no one to dig them up.
21
Q

What are the ads and dis of overhead cables?

A
  • relativelt cheap to link between tall towers
  • easy access to maintain cables
  • open to air cooling of cables

Dis:

  • ugly, ruin landscapes
  • vulnerable to weather
  • must cut across large amount of land
22
Q

How do fuses work?

A

-The fuse breaks the circuit if a fault in an appliance causes too much current flow.
-This protects the wiring and the appliance if something goes wrong.
-The fuse contains a piece of wire which melts easily.
-If the current going through the fuse is too great, the wire heats up until it melts and breaks the circuit.

23
Q

Fuses in plugs are made in standard ratings. The most common are:

A

3 A, 5 A and 13 A.
-The fuse should be rated at a slightly higher current than the device needs:
• If the device works at 3 A, use a 5 A fuse
• If the device works at 10 A, use a 13 A fuse

24
Q

Residual current circuit breakers, RCCBs, protect some circuits. They detect a difference

A

in the current between the live and neutral wires. RCCBs work much faster than fuses do.

25
Q

Live wire

A
  • brown
  • provides the alternating difference from the mains supply.
26
Q

Nuetral wire

A
  • Blue
  • nuetral wire completes the circuit.
  • when the appliance is operating normally, current flows through the live and nuetral wire - around 0 V
27
Q

Power, energy transferred, time

A

Energy (J’) = power (W) x time (s)

E =. Pt

28
Q

Earth wire

A
  • green and yellow
  • for protecting the wiring
  • and for safety
  • stops the appliance casing from becoming live
  • doesn’t usually carry a current - only when there’s a fault, at 0 V
29
Q

Watts (W) = Joules per second (J/s)

A

1W = 1 J/s

30
Q

Power, potential difference, current

A

Power (W) = potential difference (V) x Current (A)
P = V X I

31
Q

Power, current, resistance

A

P = I (squared) X Resistance

32
Q

Current, coulomb, time

A

Current (A) = Coulomb (charge flow, C) DIVIDED BY time (s)

33
Q

A (amps) = Coulombs per second (C/s)

A

1 A = 1 C/s

34
Q

Energy transferred, charge flow, potential difference

A

Energy transferred (j) = charge flow(C) X Potential difference( (V)

Physics GCSE (15 decks)

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