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Paper1_Electricity_Physics > Paper1_electricity_physics > Flashcards

Paper1_electricity_physics Flashcards

1
Q

What do circuit symbols show

A

Circuit symbols show components in a circuit and how they are connected

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2
Q

Define current

A

Current is the rate of flow of charge in a circuit

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3
Q

What is potential difference

A

Also know as voltage is the difference in potential charge/energy between two points of a circuit, which causes a current to flow

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4
Q

Define charge

A

Charge is the amount of electricity travelling through a circuit

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5
Q

What is resistance

A

Resistance is anything that shows the flow of charge around a circuit, usually caused by electrons colliding with ions in a material

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6
Q

What is a series circuit

A

A circuit with a single loop of wire

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7
Q

What is a parallel circuit

A

A circuit with two or more loops (branches) of wire

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8
Q

What must there be in a closed circuit for a charge to flow

A

For electrical charge to flow through a closed circuit the circuit must include a source of POTENTIAL DIFFERENCE

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9
Q

What is an electric current

A

The flow of electric charge, normally electrons around a circuit

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10
Q

What is the same at any point in a series circuit

A

In a series circuit the CURRENT is the same at any point of the loop

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11
Q

What is the formula for charge flow

A

Charge flow(c)= current (a) x time (s)
Q=It

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12
Q

What affects the current through through a component

A

The current through a component depends on the RESISTANCE of the component and the POTENTIAL DIFFERENCE across the component

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13
Q

What happens if the current is smaller than the resistance

A

The greater the resistance of a component THE SMALLER THE CURRENT FOR A GIVEN POTENTIAL DIFFERENCE ACROSS THE COMPONENT

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14
Q

What is the formula for potential difference

A

Potential difference(v)= current(a) x resistance
V=IR

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15
Q

What affects resistance

A

Resistance depends on the COMPONENTS AND LENGTH OF THE WIRE USED

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16
Q

What happens if the wire is longer

A

The longer the wire THE GREATER THE RESISTANCE

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17
Q

What is the name given to resistors that have a fixed value

A

Some resistors have a fixed value which doesn’t depend on the current flowing through the circuit, they are called OHMIC CONDUCTORS

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18
Q

What does the Ohm’s law state

A

THE CURRENT THROUGH AN OHMIC CONDUCTOR ( AT A CONSTANT TEMPETATURE) IS DIRECTLY PROPORTIONAL TO THE POTENTIAL DIFFERENCE ACROSS THE RESISTOR

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19
Q

What do you see on a graph when results are taken from an ohmic conductor

A

Ohmic conductors PRODUCE A STRAIGHT LINE which goes through the origin

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20
Q

What happend if the current increases in a filament bulb

A

As the current increases THE TEMPERATURE OF FILAMENT INCREASES THEREFORE THE RESISTANCE OF THE FILAMENT LAMP INCREASES

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21
Q

Name a non-ohmic conductor

A

FILAMENT LAMP

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22
Q

Name objects where the resistance is not constant

A

The resistance of components such as LAMPS, DIODES, LDR’S is not constant ,it changes with the current through the component

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23
Q

Describe the features of diodes

A

diodes are electrical components THAT ONLY ALLOW A CURRENT TO FLOW IN ONE DIRECTION, HAVE LOW RESISTANCE IN THE FORWARD DIRECTION BUT A HIGH RESISTANCE IN THE REVERSE DIRECTION

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24
Q

Describe LDR’s

A

LDR’s are types of resistors where THE RESISTANCE VARIES WITG LIGHT INTENSITY, RESISTANCE DECREASES AS LIGHT INTENSITY DECREASES

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25
Q

Where are LDR’s used

A

USED IN SWITCHES TO TURN STREET LIGHT ON WHEN IT GETS DARK

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26
Q

What is one formula for power

A

POWER/RESISTANCE (R) = POTENTIAL DIFFERENCE (V) X CURRENT (I)
P=VI

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27
Q

Name the other formula for power

A

POWER (P) = CURRENT^2 (I) X RESISTANCE (R)
P= I^2 R

28
Q

What can be added to get a range of potential differences and currents

A

To get a range of potential differences and currents a VARIABLE RESISTOR CAN BE ADDED TO THE CIRCUIT OR THE INPUT POTENTIAL DIFFERENCE CHANGED

29
Q

Describe a series circuit

A

SAME CURRENT THROUGH EACH COMPONENT, TOTAL POTENTIAL DIFFERENCE OF THE POWER SUPPLY IS SHARED BETWEEN THE COMPONENTS, TOTAL RESISTANCE OF THE TWO COMPONENTS IS THE SUM OF RESISTANCE OF EACH COMPONENT

30
Q

Describe parallel circuits

A

POTENTIAL DIFFERENCE ACROSS EACH COMPONENT IS THE SAME, TOTAL CURRENT THROUGH THE SEPERATE COMPONENTS ON EACH LOOP, TOTAL RESISTANCE OF TWO RESISTORS IS LESS THAN THE RESISTANCE OF THE SMALLEST INDIVIDUAL RESISTOR

31
Q

What does a direct potential difference produce

A

A direct potential difference produces A DIRECT CUREENT

32
Q

What is a direct current

A

A direct current (dc) is A CURRENT IN WHICH THE CHARGE CARRIERS MOVE IN ONE DIRECTION

33
Q

Give an example of an object that has a direct current

A

BATTERIES

34
Q

What will an alternating potential difference produce

A

An alternating potential difference WILL PRODUCDE AN ALTERNATING CURRENT

35
Q

What is an alternating current (ac)

A

A CURRENT IN WHICH THE CHARGE CARRIES MOVE BACK WARDS AND FORWARDS

36
Q

Give an example of a thing that uses an alternating current

A

MAINS ELECTRICITY

37
Q

What happens to the demand of electricity during adds

A

Mains supply changes slightly which is why WHEN ADDS ARE ON DURING A BIG SHOW LOTS OF PEOPLE PUT THE KETTLE ON SO DEMAND INCREASES

38
Q

What does the brown wire do

A

BROWN, LIVE WIRE, CARRIES ALTERNATING POTENTIAL DIFFERENCE FROM THE SUPPLY

39
Q

What does the blue wire do in a plug

A

BLUE, NEUTRAL, COMPLETES THE CIRCUIT

40
Q

What is the function of the yellow/ green wire

A

YELLOW/GREEN, EARTH WIRE, SAFETY WIRE TO STOP APPLIANCE COMING LIVE earth wire is at 0v

41
Q

What does the earth wire do if there is a fault

A

THE EART WIRE CARRIES A CURRENT if there is a fault

42
Q

Why is the live wire (brown) dangerous

A

The live wire may be dangerous as WHEN A SWITCH IN THE MAINS CIRCUIT IS OPEN A PERSON COULD COMPLETE THE CIRCUIT TO THE GROUND AND GET ELECTROCUTED as the current will flow through them

43
Q

What happens if the live wire and earth wire inside a plug touch

A

Any connection between the live wire and earth wire CAN CAUSR A CURRENT TO FLOW, POTENTIALLY CAUSING A FIRE ( IF CURRENT IS TOO HIGH) OR ELECTROCUTION IF A PETSON MAKES THE CONNECTION

44
Q

What is the power rating of an appliance

A

THE RATE AT WHICH ENERGY IS TRANSFERRED TO THE APPLIANCE

45
Q

What do electrical appliances do

A

Electrical appliances CONVERT ELECTRICAL ENERGY from ac mains or batteries INTO MORE USEFUL FORMS

46
Q

What do lightbulbs do with electrical energy

A

Lightbulbs CONVERT ELECTRICAL ENERGY INTO LIGHT ENERGY

47
Q

What are the formulas for work done

A

ENERGY TRANSFERRED (J) = POWER (W) X TIME (S) E=Pt

ENERGY TRANSFERRED = CHARGE FLOW (C) X PD (V) E=QV

48
Q

What is the national grid

A

The national grid is A SYSTEM OF CABLES AND TRANSFORMERS LINKING POWER STATION TO CONSUMERS

49
Q

What is the role of the step up transformer

A

Step up transfromet is USED TO INCREASES THE POTENTIAL DIFFERENCE FROM THE POWER STATION TO THE TRANSMISSION CABLES AND DECREASE CURRENT

50
Q

What do the steps down transfromers do

A

Step down transformers are USED TO DECRESE THE POTENTIAL DIFFERENCE TO A MUCH LOWER VALUE FOR DOMESTIC USE IN HOMES AND INCREASE CURRENT

51
Q

What does the electric current generate when it moves through electrical wires

A

Electric current generates HEAT as it moves through electrical wires

52
Q

Why is electricity transmitted at a very high potential difference and low current

A

When electricity is transmitted at a very high pd and low current it means LESS ENRGY IS WASTED MAKING THE SYSTEM MORE EFFICIENT

53
Q

Why is a lower potential difference used in the home

A

AS IT IS SAFER

54
Q

What are pylons for

A

PYLONS CARRY OVERHEAD POWER CABLES WHICH CONTAIN THE HIGH VOLTAGE ELECTRICITY FROM WHERE IT WAS GENERATED

55
Q

Why are step up transformers used

A

INCREASING PD WILL DECREASE CURRENT, LOWER CURRENT MEANS LESS HEATING OF THE POWER CABLES, LESS ELECTRICAL ENERGY WASTED AS HEAT, MAKES TRANSMISSION PROCESS MORE EFFICIENT

56
Q

Name the two types of charges

A

POSITIVE (+) and NEGATIVE (-)

57
Q

What happens when two electrical charges are placed near each other

A

When two electrical charges are placed near each other THEY EXERT A FORCE ON ONE ANOTHER the direction of the force depends on the electrical charges

58
Q

Are electrostatic forces contact or non-contact

A

Electrostatic forces are an example of NON-CONTACT FORCES

59
Q

Explain friction

A

When certain INSULATING MATERIALS ARE RUBBED TOGETHER THEY BECOME ELECTRICALLY CHARGED, NEGATIVELY CHARGED ELECTRONS ARE RUBBED OF ONE MATERIAL ON TO THE OTHER, THE MATERIAL THAT GAINS ELECTRONS BECOMES NEGARIVELY CHARGED, THE MATERIAL THAT LOSES ELECTRONS IS LEFT WITH AN EQUAL POSITIVE CHARGE

60
Q

Give an example of where friction happens

A

For example RUBBING A PLASTIC ROD (COMB) ON SOME MATERIAL WILL CAUSE A TRANSFER OF ELECTRONS, PLACE THE CHARGED ROD ABOVE BITS OF PAPER AND THE PAPER WILL GET ATTRACTED TO THE ROD BECAUSE THE OPPISETLEY CHARGED PARTICLES ARE ATTRACTED TO THE ROD

61
Q

What does a charged object create around itself

A

A charged object creates an ELECTRICSL FIELD around itself

62
Q

Where is an electric field strongest and the weakest

A

The electric field is strongest CLOSE TO THE CHARGED OBJECT, THE FURTHER AWAY FROM THE CHARGED OBJECT IS WHERE THE FIELD IS WEAKER

63
Q

What happens when a second charged object is placed into the electric field

A

When a second charged object is placed in the field IT EXPERIENCES A FORCE, the force gets stronger as the distance between the objects decreases

64
Q

What is the electric field

A

REGION AROUND A CHARGED PARTICLE WITHIN WHICH A FORCE WOULD BE EXERTED ON ANOTHER CHARGED PARTICLE

65
Q

What happens when the electric field strength of a charged object is greater than the dielectic field strength

A

When the electric field strength of a charged object is greater than the dielectic field strength A SPARK CAN OCCUR. This is because when the dielectic field strength is exceeded there is an increase in free electrons in the air allowing the air to conduct electric and a spark is produced

66
Q

Define dielectic field strength

A

THE MAXIMUM ELECTRIC FIELD STRENGTH, usually air, CAN HAVE WITHOUT BREAKING DOWN

67
Q

What are lines of force

A

IMAGINARY LINE WHICH REPRESENTS THE STRENGTH AND DIRECTION OF A MAGNETIC, GRAVITATIONAL OR ELECTRIC FIELD

Paper1_Electricity_Physics (7 decks)

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