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current electricity Flashcards

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1
Q

what is electricity

A

flow of charges through a conductor

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2
Q

when does a current flow

A

when charges flow from one point to another

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3
Q

what is a conductor made up of

A

metal atoms which have negatively charged electrons that can move when attracted or repelled.

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4
Q

what is a conductor made up of

A

metal atoms which have negatively charged electrons that can move when attracted or repelled.

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5
Q

what are electrons attracted and repelled to in simple circuit

A

repelled by negative terminal of battery and attracted to positive terminal of battery if there is a path that runs between 2 terminals, resulting in current in path

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6
Q

how does current flow

A

from positive to negative

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7
Q

conventional current

A

convention used rather than tracking electron flow

flow of positive charge from positive terminal of battery through circuit to negative terminal of battery

not correct -created when structure of atom was unknown

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8
Q

circuit

A

path for charges to flow
(closed circuit)
cant open in open- incomplete

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9
Q

short circuit

A

direct path from positive to negative terminal
current takes path of least resistance
bad- cause batteries to drain quickly and overheat

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10
Q

current

A

(I)

rate of flow of charge

no. of coulombs of charge that flow past a point in a circuit every second
measured in Amperes (A) using ammeter connected in series

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11
Q

ammeters

A

allow charges to flow through them in order to measure quantity of charge that passes a point each second

doesn’t use any energy or obstruct flow

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12
Q

how is energy supplied to charges and circuit

A

by battery (provides electrical potential energy)

charges carry energy to circuit - changed into other forms by components in circuit (lightbulb,motor)

energy ‘used up’
charged not ‘used up’ - just carry energy through circuit

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13
Q

potential difference

A

(V)

work done per unit positive charge

messured in volts (V) using voltmeter connected in parallel

measured across component in circuit that uses up energy

comparison of energy carried per unit charge at 2 diff points in circuit-difference

provides push/force on charges allowing them to move through circuit

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14
Q

how does battery have potential difference across ends

A

because supplies energy (ability to do work) to each unit of charge (Q- measured in Coulumbs-C) that passes through it

potential difference provides push/force on charges allowing them to move through circuit

potential difference of battery also called voltage pf battery

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15
Q

voltmeter

A

compares 2 points and finds potential difference between them
— potential energy supplied per unit charge

no charges flow through voltmeter

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16
Q

resistors

A

anything in circuit that slows down flow of charges

electrical appliances

protect other components by restricting amount of current flowing

regulate potential difference across components, allowing them to function efficiently

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17
Q

resistance

A

materials opposition to flow of electric current

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18
Q

examples of resistors

A

lightbulbs, heaters, motors, electronic appliances

simple electronics device that only there to change rate of flow and decrease current

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19
Q

opposite of conductor

A

insulator

20
Q

relationship between resistance and current

A

more resistors added
more current decreases

high currents— low resistance
high resistance— low currents

21
Q

if resistance too high

A

energy lost
if resistance in high voltage transmission lines too high- heat up and much energy (thermal energy) lost to surroundings

22
Q

if resistance too low

A

if resistance in element of geyser or electric kettle too low, won’t heat up

23
Q

when charges move through a resistor

A

collide with other charges and nuclei of substance of which resistor is made

during collision- kinetic energy transferred to particles (in the way) and resistor heats up

24
Q

4 factors of resistance of conductor

A

length- longer the conductor, greater the resistance

thickness/cross sectional area- greater cross sectional area, smaller the resistance

temperature - hotter the conductor, greater the resistance

conductor material- some materials have greater resistance to electric current

gold,silver,copper - good conductors
tungsten,nichrome- less effective

25
Q

resistance formula

A

resistance = voltage over current

R= V/I

26
Q

resistors in series relationship and formula

A

increase total resistance of circuit decrease total current in circuit

more resistors connected in series, more resistance in circuit

Rseries = R1 + R2 (however many)

27
Q

relationship between current in circuit and the total resistance in the series circuit

A

inversely proportionate - more resistors, more difficult for current to flow

28
Q

current in series circuit

A

constant through out

29
Q

potential difference in series circuit

A

splits between resistors in connection in proportion to their resistance

Vtotal= V1 + V2 (however many)

30
Q

cell

A

an electrical power supply

31
Q

variable resistor (rheostat)

A

A type of resistor that can be adjusted
to give a range of resistances

32
Q

ohms law

A

current through a conductor is directly proportional to the potential difference across the conductor at constant temperature

33
Q

resistance in parallel circuit

A

the more resistors, the less resistance
- more pathways, more current can flow

34
Q

current in parallel

A

splits between branches/resistors

resistor w higher resistance- lower current

35
Q

series circuit

A

components connected one after each other- 1 path

1 path for current to flow
-current constant throughout
-current slows—> low current

resistance splits Rtotal=R1+R2+R3
more resistors = more resistance

potential difference splits Vtotal=V1+V2
as resistance in increases, current decreases
total voltage of series circuit equal to sum of voltage of all resistors in circuit
-current circuit

36
Q

parallel circuit

A

all positive terminals connected,all negative terminals connected
-many paths
-more pathways for current to flow
-higher current
current splits in inverse proportion to total resistance
Itotal=Itop branch +Ibottom branch

potential difference constant Vtotal=V1=V2=V3

more resistors- less resistance
more pathways for current to flow
therefore resistance v current ^

1/Rparallel= 1/R1 + 1/R2

37
Q

W

A

energy
ability to do work

38
Q

why does temp as current flows in resistor

A

result of electrical energy converted being converted into internal energy
as charge carriers move through conductors

39
Q

power

A

rate of work done per unit time
transfer of energy from 1 object to another

40
Q

power unit

A

watt(W) = 1 J.s^-1

41
Q

triboelectric series

A

shows ease at which substance loses/gains electrons

42
Q

energy consumed by appliances

A

kilowatthours

power rating (kw) X time (h)

43
Q

cost of electricity

A

cost per kWh X no. of kWh

44
Q

emf

A

the total energy supplied per coulomb of charge by the cell
voltage across battery terminals when no current flows in circuit

45
Q

difference between ohmic and non-ohmic conductors

A

Non-ohmic conductors have a resistance that fluctuates with a change in the applied voltage, whereas ohmic conductors have a constant resistance that does not.

physics (36 decks)

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