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gcses > physics topic two > Flashcards

physics topic two Flashcards

1
Q

what is the function of a Switch (open)

A

Electricity can’t flow

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2
Q

what is the function of a Switch (closed)

A

Completes the circuit (lets electricity flow)

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3
Q

what is the function of a Cell

A

Provides PD and current for a circuit

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4
Q

what is the function of a battery

A

Provides PD and current for a circuit

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5
Q

what is the function of a lamp/bulb

A

Converts electrical energy to light energy

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6
Q

what is the function of a resistor

A

Slows down current and voltage

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7
Q

what is the function of a voltmeter

A

Measures PD – volts

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8
Q

what is the function of an Ammeter

A

Measure current – amps

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9
Q

what is the function of a fuse

A

Melts if current gets too high to stop electricity

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10
Q

what is the function of a diode

A

Forces current to only flow in one direction

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11
Q

what is the function of a Light Emitting Diode (LED)

A

Same as diode but gives off light

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12
Q

what is the function of a Variable Resistor

A

Can be used to change the resistance

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13
Q

what is the function of a Thermistor

A

The higher the temperature, the lower the resistance

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14
Q

what is the function of a Light Dependant Resistor (LDR)

A

The higher the light intensity, the lower the resistance

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15
Q

what is charge

A

Charge is the amount of electricity travelling through a circuit.

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16
Q

what is current and what is it measured in

A

a flow odd charged particals - measured in amps

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17
Q

what is voltage and what is it measured in

A

a measure of the difference in energy between one part of a circuit and another (How fast electrons move) - measured in volts

18
Q

what is resistance and what is it measured in

A

the opposition to the flow of electric current in a material or circuit (Slows down current and voltage) - measured in ohms

19
Q

what is potential difference

A

and what is it measured in

20
Q

what does the resistance in a circuit depend on

A

The resistance in a circuit will depend on the components used in the circuit as
well as the length of wire used in the circuit. The longer the wire, the greater the
resistance.

21
Q

what a a Circuit in series

A

Series circuits consist of one loop of wire.

22
Q

give features For components connected in series

A

there is the same current through each component

the total potential difference of the power supply is shared between the components

the total resistance of two components is the sum of the resistance of each component.

23
Q

what are Parallel Circuits

A

Parallel Circuits consist of two or
more loops (branches) of wire.

24
Q

give features For components connected in parallel

A

the potential difference across
each component is the same

the total current through the
whole circuit is the sum of the
currents through the separate
components on each loop
(branch)

the total resistance of two
resistors is less than the
resistance of the smallest
individual resistor.

25
Q

describe the IV Characteristics REQUIRED PRACTICAL

A

1) Measure the current in resistor using ammeter
2) Measure the p.d. across resistor using voltmeter
3) Vary the resistance of the variable resistor
4) Record a range of values of current and p.d.
5) Reverse connection of resistor to power supply
6) Repeat measurements of I and V in negative direction
7) Plot a graph of current against p.d.

25
Q

what is ohms law

A

The resistor follows Ohm’s law (it’s an Ohmic conductor) and its resistance is constant.

26
Q

Explain, in terms of the electrons and ions inside the filament, why both the temperature and the resistance increase

A

Ions in lamp/resistor vibrate faster
Electrons collide more with the ions
Increasing resistance and decreasing
current

27
Q

what is something if its non-Ohmic.

A

it doesnt follow ohms law

28
Q

what happens to to the resistance of LDR with increasing light intensity

A

resistance decreases

29
Q

describe Circuit resistance REQUIRED PRACTICAL

A

1) Have 3 lengths of wire (10cm, 20cm, 40cm) measured with a ruler
2) Measure current and potential difference using an ammeter and voltmeter
3) Take repeat readings and calculate a mean
4) Switch off circuit in between each reading to allow wire to cool
5) Calculate resistance by using: r = v / i
6) Plot a graph of resistance against length

30
Q

what is direct current

A

Direct current moves in one direction only

31
Q

what is alternating current

A

Alternating Current repeatedly reverses direction

32
Q

what is The UK mains supply

A

The UK mains supply is 230 V. and has a frequency
of 50 Hz (50 hertz)

33
Q

what are the components of a plug

A

Live wire (brown) – Carries
current and voltage (230V)

Neutral wire (blue) –
Completes the circuit (0V)

Earth wire (green + yellow
stripes) – Earths appliance

Fuse – Wire inside melts if
current gets too high

34
Q

what is the purpose of earthing appliances

A

if live wire touches case
current flows to earth

35
Q

how are plugs double insulated

A

case is made of insulator (plastic)
cable is (also) insulated

36
Q

what is the National grid

A

A series of transformers, power cables and pylons

37
Q

what are step-up transformers

A

Increases potential difference
Decreases current
Reducing thermal energy transfer to surroundings from transmission cables
Increasing efficiency

38
Q

what are step-down transformers

A

Decreases potential difference
To a safe value

39
Q

what are static charges

A

These are positive (+) and negative (-) charges.

When two electrical charges interact, they produce Electrostatic forces - non contact forces

40
Q

how does Charging by friction work

A

When two objects are rubbed together (friction), electrons transfer from one to the other.

One object will become positive and the other will become negative

41
Q

what is An electric field the region

A

the region (around a charged object) where
another charged object experiences a force

gcses (16 decks)

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