# Electrical Circuits Scan From Textbook

Electrical Circuits Scan From Textbook

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• Created on: 29-12-09 14:26

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52
V-l graphs show how lhe currenl varies as Uou change the voltage. Learn lhese lhree real well:
Differcnt Resistorq Filament Lamp
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The cumeni through a resistor (at constanl As the ie_rnperature of Current will onlg flow
lernperature) is proportlonal to voltage. the filarnent incrpases, through a diode in one
Different resis_lors have different the resistance increas.es, dlreclion, ds shown.
resistances, hence lhe different slopqs-. hence the curve.
R = "I./ara
For.the srrarghf-llnggtaphs lhe resislance of lhe componenl is sleadg and is equal to lhe inverse
of the gradienl of the line, or "l/gradient". tn olher words, rhe steepir the grap'h ihe lorryen rtre
resistance.
lf the gtaph curves, il rneans lhe resislance is- changing. tn that case R can be found for ang
point bg taking lhe pair of values (V l) from the graph and sticking them in the formula -V '.
R=
Easg.
EXAMPLE. Voltrnefer V reads G V and resistor R is
4 Q. what is lhe current lhrough Arnrne ter A?
ANSWER. Use lhe forrnula V = I x R.
we need to find l, so the version we need is
-
| v/R.
The answer is then: 6/4 which is l.S A.
In ,the end you'Il have to learn this resistanii ii furiiie.-,."
You have lo be able lo inlerprel volfage-currenl graphs for gour exam. Rernember
qlope, lhe lower lhe resisfa-nce. And gou need lo know thai equation inside oul,
- the sleeper lhe
-
back to fror*Gside
down and in swahili. eqyqlion in electiics, bar none. (p8. r mighr rer
*tT"S:no*9J"!.nAg1tff ofrrhe swahiri.) sou
Phusics 2(ii) Electriaifv nnrf fhe Afnryt

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### Page 2

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1) Variable Resistor
l) A resislor whose resislance can be changed bg twiddling a knob or sornelhin!.
2) The old-fashioned ones are huge coils of wire wilh a slider on lhem.
3) Theg're greal for allering lhe current flowing through a circuil.
Turn the resislance up, the currenl drops. Turn the resislance down, fhe currenl goes up.
2) "semicondtrctor Diod "

### Page 3

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Sgries (frgUits
Youneedtobeableiotellthedifferencebelweenseriesandpara|lelcircuil[email protected]
You also need lo know ihe rules about what happens wilh bolh tgpes. Read on.
Series Circuits AII or Nothing
l) In series -
circuils, lhe differenl
components are connected in a !ing, end lo end, belween lhe *ve
-'ve of the Power supplg (except for voltmelers, which are alwags connecled in parallel, bul
a.nd
theg don'l count as parl of the circuil).
2) lf gou rernove or disconnecl ong componenf, ihe circuil is bpken and theg atl stop.…read more

### Page 4

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Parallel circuils are much more sensible lhan series circuils and so fheg're rnuch rnore common in
real life. All lhe eleclrics in gour house will be wired in parallel circuils.
I) ln parallel circuifs, each cornponenl is separalelg connecled to the *ve and -ve of rhe supFIU.
2) lf gou rernove or disconnecl one of lhem, it will hardlg affecl lhe others af all.
3) This is obviouslu how rnosf things rnusl be connecled, for example in cars and in household

### Page 5

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Cfr:gvitg The B*sigs,
Heg, I know learn them now!
-
lsn'l eleclricilg greai. Mind gou il's preflg bad news if the words don'l rnean angthing lo gou...
-
l) etllren!-l is lhe flow of electrons round lhe circuit.
Current will onlu flow lhrough a cornponent if lhere is a
voltage across that
:2) Voltagr
cornponenl. Unit: arnpere, A.
is the drivingforce that pushes the current round.
rylrlrlrF
ffike "electrical pressure". unit: volt, v.…read more