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
what is the rule for potential difference in a parallel circuit?
the potential difference across each branch is the same as at the supply
26
what is electrical current?
flow of electrons/ amount of charge passing each second
27
what equation shows how current is conserved at a junction?
A1=A2+A3
28
what component does a directly proportional graph show for?
fixed resistor
29
# [](http://) explain the resistor graph?
current induced is directly proportional to the potential difference across it - resistance maintains the same
30
what component does the directly proportional graph (WITH CURVY ENDS) show for?
bulb
31
describe the filament lamp graph?
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
what component does the flat line with an upwards tail show for?
diode
33
explain the diode graph?
diode ha very high resistance in one direction and very little in the other - this means current can flow in one direction
34
What does an LDR do?
senses light, acts as a light resistor (resistance increases as light decreases
35
what does a thermistor do?
uses temperature and acts as a temperature sensor (resistance increases as temp decreases)