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Physics > Electricty > Flashcards

Electricty Flashcards

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1
Q

What is the Charge (A)?

A
  • Rate of flow of charge round the circuit
  • Electrons carry charge - negatively charged particles
  • Current only flow if there’s voltage
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2
Q

What is the Voltage (V)?

A
  • Drives current round circuit

* Also called - potential difference

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3
Q

What is the Resistance (ohm)?

A
  • Anything In circuit that slows the flow down

* More components = higher overall resistance

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4
Q

What happens if you Increase the Voltage?

A

More current will flow

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5
Q

What happens if you Increase the Resistance?

A

Less current will flow

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6
Q

What is the Ammeter?

A
  • Measure current flowing through component

* Placed in series anywhere in main circuit, never in parallel

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7
Q

What is the Voltmeter?

A
  • Measure voltage across component

* Placed in parallel around component, not around variable resistor or battery

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8
Q

What happens when you Vary the Variable Resistor?

A

Alters current flowing through circuit

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9
Q

What is the Mains Supply?

A
  • A.C

* Current constantly changing direction

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10
Q

What is the Battery Supply?

A
  • D.C

* Current constantly flowing in same direction

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11
Q

Voltage =

A

Current x Resistance

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12
Q

How does current in a Wire vary as you change the voltage?

A

Current through wire is proportional to voltage

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13
Q

How does current in Different Resistors vary as you change the voltage?

A
  • Current through resistor is proportional to voltage

* Different resistors have different resistances (different slopes)

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14
Q

How does current in a Metal Filament Lamp vary as you change the voltage?

A

As temperature of metal filament increases, resistance increases, curve graph

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15
Q

How does current in a Diode vary as you change the voltage?

A

Current flow through diode in one direction

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16
Q

What are Light Emitting Diodes and give an example?

A
  • Emit light when current flows through them in forward direction
  • Used for numbers on digital clocks, traffic lights, remote controls
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17
Q

What is a Light Dependent Resistor?

A
  • Changes resistance depending on how much light falls on it
  • Bright - Resistance falls
  • Dark - Resistance highest
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18
Q

What is a Thermistor?

A
  • Temp dependant resistor
  • Hot - Resistance drops
  • Cold - Resistance increases
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19
Q

What are Series Circuit?

A
  • Components connected in line, end to end, between +ve & -ve of power supply
  • Remove 1 component, circuit broken, stop working
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20
Q

What is in a Series Circuit?

A
  • Bigger supply p.d when more cells are in series
  • Current same everywhere
  • Potential difference shared between components
  • Resistance depends on number of components and type of component used
21
Q

What are Parallel Circuits?

A
  • Component separately connected to +ve & -ve of supply

* Remove 1 component, won’t affect others

22
Q

What is in a Parallel Circuit?

A
  • Potential difference same
  • Current shared between branches, total current flowing around circuit = total of all currents
  • Current through branch depends on resistance of brach - higher = harder for charge to flow, lower current
  • Total Resistance decreases when add 2nd resistor in parallel
23
Q

What is Voltage?

A

Energy transferred per unit charge passed

24
Q

What is Current?

A

Rate of flow of electrical charge around a circuit

25
Q

Power=

A

Current x Time

26
Q

What happens when a Charge drops through a Voltage?

A
  • Energy is transferred

* Bigger change in Voltage = the more energy transferred

27
Q

What is the Equation linking Energy Transferred, Charge and Voltage?

A

Energy transferred = charge x voltage

28
Q

What is the Equation linking Energy Transferred, Charge, Current and Resistance?

A

Energy transferred = charge x current x resistance

29
Q

What are the Wires in a plug and what are the Colours of them?

A
  • Live - Brown
  • Neutral - Blue
  • Earth - Green/Yellow
30
Q

What is the Voltage of the Neutral Wire?

A

0

31
Q

Where does Electricity Flow?

A

Flows in through the live wire and out through the neutral wire

32
Q

If an appliance has a Metal Case what needs to happen so it will be Safe?

A
  • Earthed to reduce danger of electric shock

* Earthed conductor never becomes live

33
Q

What are the Earth Wire and Fuse for?

A

Safety and work together

34
Q

How does Earthing and Fuses prevent Fires and Shocks?

A
  • If live touches metal case, big current flows through live & case & out down earth wire
  • Surge in current melts fuse in live wire
  • Isolates appliance, impossible to get electric shock, prevent fire caused by heating effect of large current
35
Q

What are Circuit Breakers?

A
  • Electrical safety device used in circuits

* Protect circuit from damage if too much current flows

36
Q

How are Circuit Breakers more Convenient than Fuses?

A
  • They detect surge in current, break circuit by opening switch
  • Circuit breaker easily reset by flicking a switch on device
  • So more convenient, fuses replaced once melted
37
Q

What is a Residual Current Circuit Breaker (RCCB)?

A
  • Detects difference in current, cuts off power by opening switch
  • Operate faster than fuses
  • Work for small current changes that fuses can’t melt
38
Q

Electrical Power =

A

Current x Voltage

39
Q

What is Electrical Power?

A
  • Rate at which an appliance transfers energy

* Appliance with high power rating transfer a lot of energy quickly, will draw large current from supply

40
Q

What does Energy Transferred by appliance Depend on?

A

Power of appliance and how long it is on for

41
Q

What to Like and Opposite Charges do?

A
  • Opposite - attract
  • Like - Repel
  • Forces weaker further apart
42
Q

What do Conductors do and give an example?

A
  • Conduct charge easily
  • Current can flow through them
  • Metals (copper, silver, etc)
43
Q

What is a Static Charge?

A

Charge builds up in one place and not free to move

44
Q

What is a Cause of Static Electricity?

A
  • Friction
  • 2 insulating materials rubbed together, electrons transferred from one to another
  • -ve electrostatic charge on one,+ve on other
45
Q

How can Cars get a Static Charge?

A

Gained or lost electrons from air rushing past them as travel at high speeds

46
Q

What happens as Electric Charge builds up on an isolated object?

A
  • Voltage between object & earth increases
  • Voltage large enough - electrons jump between charged object & earth - this is a spark
  • Also jump to earthed conductors
47
Q

What’s an Example of Static Electricity being Helpful using a Photocopier?

A
  • Image plate +ve charged
  • Image of what your copying projected onto it
  • White bits make light fall on plate, charge leaks away in those places
  • Charged bits attract -ve charged black powder, transferred onto +ve paper
  • Paper heated so powder sticks
  • Photocopy now made
48
Q

What’s an Example of Static Electricity being a Problem using Lightning?

A
  • Rain & ice bump together in storm clouds
  • Knock off electrons, top of cloud +ve charged, bottom -ve charged
  • Creating huge voltage & big spark
49
Q

How do you Test whether a Rod of material is Charged?

A
  • Suspend rod with known charge on thread , see if there repulsion or attraction when rod close
  • Attraction - Test rod has opposite charge to suspended rod
  • Repulsion - Test rod has same charge to suspended rod

Physics (7 decks)

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