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Physics > P2 > Flashcards

P2 Flashcards

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AP® Physics flashcards Physics 101 flashcards
1
Q

which equation links charge flow, current and time?

A

charge flow = current x time

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2
Q

which equation links p.d., current and resistance?

A

p.d. = current x resistance (IVR on triangle)

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3
Q

which equation links power, energy transferred and time?

A

power = energy transferred / time

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4
Q

which equation links energy transferred, charge and p.d.?

A

energy transferred = charge x p.d.

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5
Q

which equation links power, p.d. and current?

A

power = p.d. x current

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6
Q

which equation links power, current and resistance?

A

power = current² x resistance

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7
Q

describe the live wire

A

brown
provides alternating p.d. at about 230V
from mains supply

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8
Q

describe the neutral wire

A

blue
completes circuit
carries away current
0V

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9
Q

how does electricity flow through the wires?

A

in through live wire

out through neutral wire

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10
Q

describe the earth wire

A 
green and yellow
protects wiring, for safety
stops appliance casing from becoming live
only carries current if there's a fault
0V
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11
Q

what’s electric current?

A

the flow of electrical charge

size of the electric current is the rate of flow of electrical charge

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12
Q

what conditions are needed for electrical charge to flow?

A

closed circuit

source of p.d.

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13
Q

unit for current?

A

ampere/amps (A)

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14
Q

unit for charge?

A

coulombs (C)

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15
Q

unit for time?

A

seconds (s)

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16
Q

definition of p.d.

A

driving force that pushes charge around (the circuit)

17
Q

definition of resistance

A

anything that slows down the flow

18
Q

definition of resistance

A

anything that slows down the flow (current)

19
Q

state the relationship between resistance and current

A

the greater the resistance across a component, the smaller the current that flows
for a given p.d. across the component

20
Q

state the relationship between current and charge

A

more charge passes around a circuit when a larger current flows

21
Q

what does the ammeter do?

A

measures current

always placed in SERIES with whatever is being measured

22
Q

what does the voltmeter do?

A

measures p.d.

always placed in PARALLEL to whatever is being measured

23
Q

what’s an ohmic conductor?

A

at a constant temp.
current flowing though it is directly proportional to the p.d. across it
(resistance stays constant as current changes)

24
Q

what happens to the R value for some resistors?

A

for some the R value stays constant

for others it can change as the current changes

25
Q

what’s an example of an ohmic conductor?

A

a resistor at a constant temp.

26
Q

for which components and resistors does the resistance not stay constant?

A

filament lamps
diodes
thermistors
LDRs

27
Q

what’s the relationship between current and resistance in non-ohmic conductors?

A

resistance changes with current through the component

28
Q

describe the trend in a filament lamp

A

when an electrical charge flows through, energy is transferred to the thermal energy store of the filament which is designed to heat up
resistance increases as the temp. of the filament increases
as current increases filament heats up more and resistance increases
less current can flow per unit p.d. so graph curves/gets shallower

29
Q

describe the trend in a diode

A

current only flows in one direction

if current is reversed there’s very high resistance

30
Q

describe the trend in an ohmic conductor

A

at a constant temp.
current is directly proportional to p.d.
so the graph has a straight line through the origin

31
Q

define the term ‘I-V Characteristics’

A

refers to a graph that shows how the current flowing through a component changes as the p.d. across it increases

32
Q

what’s a linear component?

A

have an I-V Characteristic that’s a straight line

33
Q

give an example of a linear component

A

fixed resistor

34
Q

what’s a non-linear component?

A

have curved a I-V Characteristic that’s curved

35
Q

give some examples of a non-linear component

A

filament lamp

diode

Physics (9 decks)

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