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physics > Electricity and circuits -SP 10 > Flashcards

Electricity and circuits -SP 10 Flashcards

1
Q

what direction does convectional current flow in?

A

conventional current direction goes from the positive terminal to the negative terminal of the battery

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2
Q

how does a metal conduct electricity?

A

electrons can be easily removed so a metal wire has many ‘free electrons’ when a battery is attached to the wire the voltage ‘pushes’ the free electrons around the circuit.

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3
Q

why do electrons travel along the conventional direction of current?

A

negatively charged electrons attracted to positive terminal

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4
Q

what are circuit diagrams used to show

A

components and the junctions in a circuit

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5
Q

What does it mean if components in a circuit are in series?

A

one route the current can take around the circuit - so if one component fails the circuit currnt will stop

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6
Q

what does it mean if components in a circuit are connected in paralell?

A

junctions allow the current to take different routes - so each component can be switched on seperatly / there are alternate current routes so if one fails the current will take the alternate route

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7
Q

what unit is electrical current measured in?

A

amperes / amps

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8
Q

how can amps be measured?

A

using an ammeter

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9
Q

Why does the total amount of current stay the same in the circuit? what happens in parallel circuits?

A

the current is conserved - in parallel, the current splits at a junction to travel along different branches - howvere the total amount entering the junction is the same as the amount leaving

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10
Q

if i have a parallel circuit and there are 10 amps going in, how many amps will flow through one path at a junction? how will this change as the current reaches the negative terminal?

A

5 amps
10 amps

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11
Q

why is a potential difference needed in a current?

A

to push around an electric circuit

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12
Q

what is another word for potential difference in a circuit?

A

voltage

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13
Q

how does movement of electrons change when a potential difference is applied across a component?

A

the bigger the potential difference, the quicker the flow of electrons

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14
Q

what is potential difference measured in?

A

volts

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15
Q

What conditions must there be for a current to flow?

A

circuit must be closed and contain a source of potential difference

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16
Q

what is electrical charge measured in?

A

coulombs (C)

17
Q

what is potential difference? how can it be descibed?

A

pushing power causing electrons to move (slope analogy)

18
Q

what does potential difference do to a circuit in closed system?

A

causes a current to flow

19
Q

how is a voltmeter connected to a circuit?

A

in parallel with component of interest

20
Q

what is the rule for current in a series circuit?

A

it is the same everywhere

21
Q

what is the rule for voltage in a series circuit?

A

voltage is shared by components

22
Q

what is the rule for current in a parallel circuit?

A

current is conserved at junctions
(total current entering a junction equals the total current leaving the junction)

23
Q

what is the rule for voltage in a parallel circuit?

A

voltage is the same on each ‘branch’

24
Q

what is the rule for potential difference in a series circuit?

A

shared between components

25
Q

what is the rule for potential difference in a parallel circuit?

A

the potential difference across each branch is the same as at the supply

26
Q

what is electrical current?

A

flow of electrons/ amount of charge passing each second

27
Q

what equation shows how current is conserved at a junction?

A

A1=A2+A3

28
Q

what component does a directly proportional graph show for?

A

fixed resistor

29
Q

explain the resistor graph?

A

current induced is directly proportional to the potential difference across it - resistance maintains the same

30
Q

what component does the directly proportional graph (WITH CURVY ENDS) show for?

A

bulb

31
Q

describe the filament lamp graph?

A

current increases with increasing potential difference but a decreasing rate
the more current there is, the hotter the lamp becomes - resistance increases as a result

32
Q

what component does the flat line with an upwards tail show for?

A

diode

33
Q

explain the diode graph?

A

diode ha very high resistance in one direction and very little in the other - this means current can flow in one direction

34
Q

What does an LDR do?

A

senses light, acts as a light resistor (resistance increases as light decreases

35
Q

what does a thermistor do?

A

uses temperature and acts as a temperature sensor (resistance increases as temp decreases)

physics (41 decks)

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