Name of str-ident:
fHactul
ft,",rkx#
&r&M
E.'rei
_/
Physics Teacher:
Physics
A
OCR
AS Syllabus Hl58 replacing
3BB3
Module: G482
Electrons, Waves and Photons
Exam questions on electriciQ overlup the topic boundaries und
so the selection of questions here may cover other topics than
thst stated.
Topic
i
2.2.3
2.2.4
esistance
Resistivity
These questions have been taken from recent papers up to 2009,
based on specification 3883.
The old specification is a close but not perfect match and some
parts of the new specification are not covered.
Remember a separate forrnulaldata sheet is available in the
examination. You may need to look at this to answer these
questions
fJdr' ?=u/L
(a)
trl'\&\'y
Ncf Vv (:& #rpu c(uf
;f
DeJine the ohm'
Viftlr,-3l
t1l
(b)
6
5
rlA
4
.)
Z
1
n#
"0
Fig' 1'1
(i)
V
wiih the potential difference
varies
resistance
State how ihe
'.""'{;
1
acroSS the resistor
'i,o, ., ,.,.. igi; i:s
igr*sLsi.'>r€{tbrtug*
..
i#=*tt:q-usi-af
t1l
l-*-tt*t*
t1l
t
o ocF 2009
(i
i)
have
when the resistor and the filament lamp
state the value of the potential difference
the same resistance. Expl{4Xour answer'
. ?:.C)V U
*"d""""' ;; :
*-f
JA&Lta^r
TftJ.
e.,..rt t€^\'
fi = Ja;g
{o,L
o
C)'€=+g
:
\r
gll'lG
5.tA
Ir=
{s'- i'5\ u:-
+ 3-b =
-- \. S1rr t.\ t
t'$+t
rJ=-L
\ t\ l'tt
s7r
["t\
: 0'bs
resistance =
beIC
o'\oL\s 61 0 'U.+ w
Ou(o
5
a'. O'
:,CA'-e\
fTotat:
r
b3
6
Turn over
B]
E5
(a)
fi
"fi t)
(b)
t1l
(c)
Fig.5.1
The battery has e.m.f. E and negligible internal resistance. The resistances of the resistors
are R and 2fr. Calculate
(i)
the total resistance of the circuit in terms of R
t-\ L
-t+t-"
t-
t
\._
!'
t-r
f :=
(fKL
+L
-.F-
lj
(ii)
i:. 1\a.
f\L
*..
.iF:
.l
h"jt
ti= :
*
the current from the battery in terms of E and R.
v/' !
lr-
:=
'e-
.,3:^
q:: i
i'5.9'r
\3"
0,Lta^l
4
-
'b*ii--
*
=
5t:'
&*,-
:7
0
current =
v I P+l^e/
[Turn over
r
ffiil ilil lill lluilil|uillilll llil ilil lil lllt
(d)
Fig.5.2 shows a circuit.
0.16A
36fl
18O
I
Fig.5.2
The battery has negligible internal resistance.
Determine
(i)
the charge passing through the battery in a time of 150s
oA /So
q) =:Lb
o'+8
1z
7Z
charge =
(ii)
the number of electrons responsible for the charge in (i)
-72
f ,to
XIO-'
4-Sn(o-u
'
0
number
(iii)
the current
=..$:..Sd.t.O-l,,,
I in the 1BO resistor
A ? o'+s -4> 't (2
current =
I
lllll lilll llill lllillllll llll llll
ililil ilIil illll lllll
-51
61 9521
2-
..Q..:.3-2......
A
t1l
(iv)
the e.m.f. Eof the baitery.
4ft,-1 g-\n pamlul
{d\*i
R. t;'
F =[:J*
lL,=
E)3b
f 3b
t(
t]-Ltn
c:'thx
=
\\'sL = lzv
e.m.r. =
m
.........
I\.:..S.L...-..... u
tzl
[Total: 12]
[Turn over
r
ililililll
lllll
lllll lllll
-51
lill lill lllll lilll
61 9521
3.
lill
llll
(a)
(b)
4
0 nieur ftr'[{
\JI
:l f:i.p\,"-
,l
rrl ()
\
is.s
iee
's_s
i$€i
Ki-s
i€,&
Fig.3.1
b,€
(i)onFig.3.l,markapointon-thegraph,andlabelitwiththeletterM'wheretheresistance i1l
of the filament lamp is
maximum'
*o*-
;€E
"S$
icG
s-$
(ii)Calculatethepowerdissipatedbythelampwhenoperatingat6.0V.
-iL
ir$g
r€s
i€.9
bs
'S€
bc
iot
lti(
\-/
.&,* n'
ibr
i.€J
tft'.{
,",s3
jg.'(
n\
6
tlttiPr
pOWOI
If,
=
;o(
..bt
;s{
s,"(
.$t
sl
i.s.t
&J
pt
i$r
.$J
'i$i
'81
i6l
isi
,$l
i,s
i€
s
i{$
ifi
ffi
i€!
ih
I
Iilil lllil lllil lll[llllulxll
lllil
lllll lil llll
is
i€
is
(iii)
Fig' 3'2 shows the same filament lamp
and a resistor of resistan ce 1.2e connected
series with a battery.
4.5V
Fig. O.2
The battery has e'm'f' 4.5v and internal
resistance r. The voltmeter has very high
resistance. The current in the circuit is
2.0A.
1
Show, with the herp of Fig.3.1, that the
vortmeter reading is
3.4Vrr,
[,.]hqn r'- j'o n v- = r ,av fry, .g {v.fh [L)
\-/
l'L
s
A.oF
TR
\L=
-&.t+v 0
\f: td+ YL = l'O + 2-+0 = 3,+V
n0
N{ p"
Anstxr
2
\fl,',
l3l
Calculate the internal resistance rof the
battery.
, +'S-3'+ - l.lv 0
t{
y*-n
f =
T
C'SS.n-
;o
resistance =
/4.
....O.:.S.S...... a
[Turn over
I
lililt lilil tilil ililflilrufi|nll ilil ilill lilt
lill
eJ
ii\
(a) State Ohm's law.
Fig.2.1
(i) Name the component with the IlV characteristic shown in Fig.2'1-
.3....r"-..,:...':.:&:,'.u....,;.i...:!.,,:.........=..........'..1....-.F.:.-'........ ""
(i
1_\
/.,*
[].'\t-\ Ql
_),
. .- , i f-l
\ ---'
-Ll
0*',\\\
\
'r
i) In this question, one mark is available for the quality of written communication.
Describe, making reference to Fig.2.1, how the resistance of the component depends
on the potentialdifference Vacross it. You are advised to show any $lQDlations.
It/
1....:.,,1.,,.1:r,;.-...,.,*.-,:i.......hi.......i.!...::...1....;1...........-:'i!':...':.'..;..'.'-...Y:..'.-.....-..""
Ir
...1.;*...\.,,r. ...:..i.,..\....,.,..r...,.l:. ir:;.,...)r,...:g..,.
o
r
n
-alf
ruLtti,*
W\^it- *
A, \'
t1]
Jr,l:".
-.: ,..;n
,...[ *,. .. r.:i,,
b.... !.
,
... r. 1,.. ..-.......$ L{"{.t, ..
,...i.t. '
. t .*, LL
Exaninels
Use
(i)
qlltu
(b)
Fig.3.1
Calculate the total resistance between A and B-
&= f,€: O
bo
J-:++l
g- R..Ru
(,.+Rr
te= Lg-lt r ; b.*,n- Q:,
lc+i5
]*{'
at
go-L[c*r
{*rui R-=a0H. : S'b
resistance
= ............e*
O
.......o
t3l
For
Exaninefs
(c)
i)
Fig. 0.2 shows a negative temperature coefficient (NTC) thermistor connected lo a24Y
po*ur supply of neg'iiginte internal resistance. The ammeter has negligible resistance.
Use
i
24V
I
Fig.3.2
(i)
P=
When the switch S is closed, the ammeter reading is 28 mA. Calculate the power
dissipated bY the thermistor.
avo
s-+}.
=
&a n
ro-) 0
+O
,[ \o?".o"
O '\r*t 1_
I
(ii)
A few minutes after closing the switch, the current has increased to a constant
ffotal: 10]
I
[Turn over
J
(a) Draw a line from each of the named
components on the left-hand side to the correct 1-v
characteristic on the right-hand side'
metallic wire at constant temperature
semiconductor diode
filament lamP
0
'-
o1l
co{ieth
I
lllilt il|il lllil
llu[$|ul$ll
lllil
lllll lil llil
=
e
{tf
L
c
-
(b)
i
communication'
ln this question, two marks are available for the quality of written
each component below'
Explain, in terms oi resistance, the shape of the 1-Vgraph for
F
f
{
F
g
t
i
4.
F
=
F
{
I
N
$
4
*
!\
=
:t
sx
*
{,
+
=
i
(ii)
it
*
=
t\
*
llt
l*
tft
lir
i{
*
i{
it
j;
+{
'j':"'
li(
!!
it
,r{
x$
(iii)
r!
lil
lif
It
li{
{
., {\\^}'
"n n\
t6l
(i-'UfCq
- {iq
fi
)\l
' BJf
L$ L\-\gv=- C-\+€
Qun- C1v€'::\rc
"r-1't\tl
fn}:u+*-\\
Lt\:u':e
\
vLVv
i{
PQ"-
*yf
,ll
F>
O "tu u*wP\e ssr:LJc-t*
S\rlcLv te c'(
}J
;l
'+j
*
t
d
'*
5pu-3
!x
[Total:9]
*- \
1t
it
-/-)
rv\UC wduality of Written Communication l2l
\L'
)\ A;
1.Y\'*
\
- =)
tr
\')
*-}-r\c'-* '"J* S1);:ur.-*'i
\
\
cv-
r-, ..- -. -r
t'
[,,i.:l.,Vr.rr",Cu,[t(i,-\
'"t - -
i\'*")
[Turn over
*
;t
it
.{
fl
fl
s
u'i':1'-ii'
r
ffiilr lltil lllll
llu$il|rulxtl ilil llffi llll lllt
I.
A cell, a resistor of resistance 120fJ and a negative temperature coefficient (NTC) thermistor are
connected in series.
(a)
ln the space below, sketch a circuit diagram of this arrangement.
L
--;
I
I
Ccl re ct"
0
r.---'
s-1 rw-,l*'\i
l+r CrL\ - *\JJ\,c,'.,ttc,r-i
t-J
iY:,:trr
,n^AJ y\-*-"\W''f
.^l.L
U tL(tacv'CJLTJ
(b)
pl
The cell has e.m.f. 1.4V and negligible internal resistance. At a particular temperature, the
current in the resistor is 5.0 x 10-3A.
(i)
Calculate the potential difference across the resistor.
0
potential difference =
(ii)
*," " [r
V
g
IzJ
Calculate the resistance of the thermistor at this temperature.
P
=-l? '
.
- rlr
-r\.Ln
trt -o.bD
'
tqi
it.*.**
'
f-r
r'
:"^
i 1
G[p" V \w" tr,\c-t' L
r'Yq.u
C'r,\t.,-lV"Kr*-(b)
-how {{0-}
State and expldin
'*-r
:
r.-,
n
/
I
\-'-
r\resistance
CKCrr-
=..........]..{.
...........o l2l
the potential difference across the resistor changes when the
temperature of the thermistor is lower.
llllllllllll lllll llillililt illilililt
'51 61 95204.
ililt ilil1
ilil ilil
(a) The llv
eharacteristic of a particular component is shown
in Fig. 1.1.
2.A
I/A
1.0
Fig. 1.1
(i)
(ii)
Name the
'
component.
(ft{a;r*nn} i*rnp
f
/:x
fo*" U
According to one student, lhe 'gradient of the graph
at 2.0v can
the resistance of the componenl at 2_0V,.
Explain why the student is wrong.
kt"ui.sn"*ic........ ii".n u1n**
\
\
..1oi.......:.:.'$i ***g*..sr*"+"th
(iii)
..
Ji";,#*,
:i
i-en
i.J
t.
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li
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i
4f+r+dxs,r.?o_ ..... .. ...
U
s
(
E
0
$
€
F
€
e
e
p
e
E"*f-
la
used to determine
...................111
Determine the resistance of the component at 2.0V.
it
be
n
,4.
u
r1l
:l
$l
n
g
ff
B
s;
g
er
t
a
3
J
resistance =
I
I
8un \"1
OJ
oj
sto;{:O
ci,
o1
9t
pl
Ol
il
-$."1
dl
d
CIJ
oi
pi
l-.
o",
9J
p;
,oon
91
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I
Iilil
illil
tilil iltil iltil ililt ililt
. 5021 83304 -
illil
ilil til ilil
e{
ei
ot
t:,
I
(b)
il
t
I
i
F of a different component with
Fig. 1.2 shows a sketch graph of the variation of resistance
potential difference (voltage) V'
tl
ft
R
*,
$i
R
"$
ryi
Rj
Bi
R
R*
E;
R
Fig. 1.2
R
.Rj
'ffii
$l
B
ffi
C, f r..j\,<"-,
:ft
iff
ift
I S'* 3 *'turi-.]
IR
iBr
;RJ
ifi
'ft
I$
l"Rj
TE
fR
#,ffi
Fig. 1.3
;fi
.i,,ff
the IIV characteristic of the comPonent'
Complete Fig. 1.3 by drawing a sketch graph to show
DRl
l2l
.3.-r.Ri
a#
di#
ffi
OR
-in1
cfi
0$
rt$
CR
e,g'
ff#
cn
rcB
ffi
r'GR
lO;R
t0.'r
)..e.R:
j
)@-,R:
ffi
)cR
lci+
llda
i*eH;
ffi
?cB,
l-c-Rr
l-.o"r
furn ou",
roon
?i-q,,;S.,
rc"R
ffi
I
ilril
lllil
lllll
lllil
ilill llill ilil
ilIil
llill lil llil
J
(c)
Fig. 1.4 shows an electrical circuit containing a semiconductor diode.
120f2
variable
supply
Fig. 1.4
This diode has a very low resistance when it conducts. lt has an infinite resistance when
the potential difference across it is less than 0.6V. The variable supply is adjusted to give a
reading of 0.4V on the voltmeter.
(i)
State the current in the 120f) resistor.
current =
(ii)
o
0
A [1]
State the potential difference across the diode.
potential difference
= ............C .:.:rt
v [1]
lTotal:8]
f-to"oroon
I
lllilt
lliltillfillillllllllllll lllll lllillllll llllllll
" 5021 83306 -
r
3
A negative temperature coefficient (NTC)thermistor is connected across the terminals of a battery
of e.m.f. 6.0V and of negligible internal resistance. Fig. 3.1 shows the variation of current / with
time f from the moment the thermistor is connected to the battery'
r
110-3A
0102030
Fig.3.1
(a) Calculate
pqPower dissipated by the thermistor at time f = 0.
T*NV
b'* x
5firrCI*3
t,?-Li
&-l&, o,x=@
(b)
fr)u)
o
j
GA\ L^)ry '*1\rusk ttuc[l.j(
L
CWC
--t
t
pVrui\tS v{Vi.oU' C}i[gn'up\,E
f''
Qualitv of written communication [2]
Gl:..^-'e-n-
qt'€lfic''^ ]
Slruc[ura "Sc-tisch".'
0
'\L-;-*.** [i: f>n4,LLu.p + ,t\ru\{\Aar
\rilililllilililililililililillilIililil]illllllllllll
v- r
[rotar:8]
I
For
Examinef:
Use
Fig.Z.1
The ammeter and the battery have negligible resistance and the voltmeter has an
infinite resistance.
The copper wire has length 1.8 m and diameter 0.27*rnm. The resistance of the wire is
0.54f2.
fr=rT
{)=
t
*.sr+ x
a FE
O
A5
{nt
t
/.8
I
t l'f
r'
].r
ds-*
resistivity =
,'"?Lr fs-r
&"- \oo'o*c^/'
r-[o-u a€)
1"b.\1
J}-fir\fn 4'
f-t(
d
&wn
udpd
s
(ii)
ln this question, one mark is available for the quality of written communication-
State and explain the effect on the ammeter reading and the voltmeter reading
o
. 4\"4
'5:r,+re- a**'',r->
il\e,K(
-BP[tYf *rjic'rn.ttc"i
Qutt
U
[Turn over
(a)
in terms of the length L of a conductor, its
0t-l6
l*
(b)
surq3*c u.
..
.11I
Fig.4.1 shows a cube made from a material of resisiivity p.
,r{
/7-
)------l----
,/
0.5m
Fig. 4.1
Determine ihe resistance between any two opposite faces
of the cube in terms of the
resistivity p.
^frL
,fr
(
/
n-'\
,.1\
a !*P x o't U
f g., L
O
resistance =
(c)
A metal rod has volume
(i)
A
1
.6 x 1o-5 m3,
, Setd ,rf =G
oAP
............f.....
........ t2l
length 5.3 x 1 0-2 m and resista nce 7.Bx 10-5 e.
Show that the cross-sectionar area of the rod is 3.0 x r 0-a
m2.
= l?_r ro:*
._
5- 3 vfe^z
v 3'olx
I C)-
*
fr,OLn /0
o ocR
2009
Yrno
no rwLpt
QnJule
t1l
(ii)
Calculate the resistivity of the metal.
F 3'slr rc:\
rjrd
f=
5'All*
E *'4;=$- f /*--1
bw[c[ \,\\xlo-l
= €)'
resistivity=
(d)
t ^ "n*** *. r€;)=lhlYiny
rb{frr*\
C r to-i;1\.r**ir Npp u* r:rn-* H fl*'
,/'
^
'u'ti
rstr )t
*,5\i,J\U1
p_i.
k"i
ff .v*
[U
12]
fTotal: 8]
Turn over
r
f
in plastic insulation'
Fig.4.1 shows an electrical cable consisting of bare copper wires encased
copper wlres
plastic
insulation
Fig.4.1
26 copper wires and is_12.0m long. The radius of each copper
wire is 3.50 x 10-5m.The resistivityof copper is 1.70 x 10-8f)m.
(a) A particular cable contains
I
(i)
show that the resistance of a single copper wire is about
*O =
'\ lE
R=
l.Jc
*&*,s*;,;gt o
N
\
0I{.
O'S:u,P;
Rl*
er'
2a'
\et[a.,.o-(
llillmilililll
rsl
'
O
) cFta. t\ &t" li rwa']
L.o"*roou
liltil lllll lllll
foql
,2[lt.a-r:
Ery
I
C?'
,'.4j{
L"uLLe; L- i-,'+"m.-Lir-\
rJ..,"
30 =?*O
= d.'tlLk *.O
ft,Ltuc Gross
=rt*'r?Fr*:
r+\
Explain why the resistance of fne electrical cable is abciut
"Tr,elq clb€-
n
=1?rL (t'
Tic-r ,. lt-'; a
'"'\ 5 3' .J?(ii)
53O.
lllil
llill llll llll
t1l
ir
(b)
Fig.4.Z shows two electrical cables used to connect a power supply to a lamp. Each cable
hai length 12.Am and is identicalto that described in (a).
Fig.4.2
The lamp is rated at24W,6.0V.The powersupply has negligible internal resistance and its
output is adjusted so that the potential difference across the lamp is 6'0V'
(i)
Calculate the res istance of the lamp when operating at 6.0V.
"Fdt
f,r
!=
[ "/
N
t'
={
t
_{-
',
o
;*
H
i =
Lr:
i
-;'*.j
o'o
=o
.r\
R..
tr
: \.s*
(ii)
o
Explain why the e.m.f. of the power supply is greater than 6.0v.
.;Ul LL!!.['wl-""t''':tXfgK;""'""""'
hapJ- \ m*li*'
eLLc"* hap-n
U,,*rl++ \f,r:',pq' lpi\: t,*\ Cad*f t*l =
..*.....:t':=.......i.,iL...r.:='....."
'
F*,.',8!:"#i," FSH?S"]#*,D \,*eryc-\
't
't:.
tzl
er-I
+
re
t,:
rrs\",,\e(
aq
1\
'y'
I
\\v
'=
{ls$
L-oocnzoos
e)
o
e.m.f. =
nrl
b..{Io.
D:€
Iilililtilll llil lllil-1 lllllllllllllllllilllllll
96548509t
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llll
[Total:9]
[Turn ou",
J
'
ilr,u:
-951115310'
(a)
1'
material of resistivity p. write an
A wire has length L, cross-sectional area A and is made of
of L, A and p'
equation for thJ electrical resistance fl of the wire in terms
,*.
f't\ ?
r''
I r
"
tt
il1
\t\/
:*
(b)
(c)
Y
plastic base
Fig.6'1
y
e. The rength of the carbon layer
The resistance of the carbon rayer between X and is 2200
ir i.g * 10-2m. The resistivity of carbon is 3'5 x10-5Qm'
(i)
is about 2 x 10-10 m2'
Show that the cross-sectional area A of the carbon layer
rtr :
";o
:
(ii)
>a"l'\
poI:J.i::*T,:ffiI
/er that can be safely dissipated by the
: f ::
rhelrrentdTi.resistorr'f':rflT*
5*
\
\'r
-r
L
'.
r*
r "(1p)''
"a,
,, I
\ot '=.jor\i\r\'u'^
g
*
vr"
T,'*
"'.-t,
;. *,
&-f3
I
121
Sesistor is
'" 0'50 w' calculate
li"=" _)"q
-- \
-\.,*uo\-,
.:a ,* *l f,,
!,'
t
tc lrV-'L
\' {i' 6Jb'€
+!
rhe maximum
(
i-"
*7
ililil illl
lllll
L \t)
lllll lllll lllll lllll lllll lllllllll llll
[Total:8]
ffurn over
For
Examiner's
Use
/:
- t!,'
(a)
G,$
U(b)
tal strips
rear window
Fig.5.1
(i)
State whether the strips are connected in series or in parallel.
(ii)
Each strip has length 85 cm and resistance 18 O. The material of the metal strip
has resistivity 6.9 x 1O{ fl m. Calculate
1.
the resistance of the three strips between A and
B
n
L-+I+L(/
-:
4-L
+:}-+JK K, Kr Ks tE l.} lB
l-r
iP* if"g:'o
-.,n
t\/R^= EG
2.
ls.............
cl
[Ir
r.
*\.............
w
t2l
the total power dissipated by the three strips
f: {"0 ;
.L
1i
i
1
.re\
POw€l =
3.
,0
resistance =
the cross-sectional area of each strip.
*,lf
R= f-L r.^ h
idb U;fl
=
b'q
r'trC,*b
h
rR
{t
-.
'''3j
\-b-e
/F,
-2 3'Lb F\r
Ui
( r)
cross-sectionat area =
/\
\-.
^F
..$..,.3b.,lt..{#: m2 [3]
[Total: 10]
For
Examinefs
Use
(a) The electrical resistance of a conducting wire depends
Complete the sentence below.
number of factors.
ona
10 cm
Fig.3.1
The lead is made of a material of resistivity 8.0 x 10{Qm.
(i)
nr* r..-\
lY
hr= /\ (t)
'f\ v
dt
&*
c;
l*
A
.a. .
Lr
"",^o,
:
;:n." I
N\'' I
= ,)-
ri
.4,,
:t\/
rf)
resistance = ...:.-:....{.J...........fi
14]
A student connects the ends of the pencil lead to a d.c. supply. The potential
difference across the ends is 12V Calculate the current in the pencil lead.
\ c- -t [.=
-\
\
*8.,
, .1
a'fJ r *.,*l*rs}i
h a'fi
fu
?|. l"*r
*.r- ^i
-t
lencil
!" E lTF, i'.*p{i i(l
kf
tr :. fTf*
\ d>\
o*
)
-Fr3r!l*b
l!:,'Iu.:Jtltl)
l '\
(ii)
lead
Calculate the resistance of the
a \'*
*" l\
-q*
.L
-'f ;,{b
€,
CLLU.
*tll
{,T tr\
!!
iD
current = .....
1:T
.. A t2l
[Total: 10]
2A22lJUNOz
For
Examinels
Fig.4.1 shows a car battery of e.m.f. 12V and internal resistance 0.014f2 connected to the
starter motor of a car. When the car engine is being started, the car battery provides a
current of 160 A to the starter motor.
copper
cable
copper
cable
Fig.4.1
(a)
Show that the p.d. across the internal resistance is about 2.2
V.
f= T(
=f;.Olt.t tr \bC
=
a.;LS
* 3.?v
,)
n0
ROytc Cov- GnSc^y<:
\
t1l
(b)
Determine the terminal p.d. across the battery.
{a
\?-;l-'21{
e
9-ru
= 1'g
-Uh
p.d.=
1:8
.....v
r1l
Use
For
Exaninefs
have total length 0'85 m and
(c) The cables connecting the battery to the starter motor
Use
diameter 8.0 mm.
(i)
5.0 x 10-5 m2'
show that the cross-sectional area of the cable is
h = TrcL
,L.
z Tr n f+.c) i{rdt O
= S .o3T. ro-s
F 5'C: r ls-s n^\ flo
nart {b,
a,1J u)q(
l1l
(ii)
x 10-8 Om' Calculate the total
The cables are made from copper of resistivily 1.7
resistance of the cables'
f
Lq'r$
"/
R.=,A 6=r
.D
n,or u)"d
l'1nt0-8 n c'8f
5'oFl8-5
(+o-"
ct',)
A'st F lc
- r.!
'
resistance =
(iii)
olro-)
.&
I
n I CI:o*Oo
t3l
if the cable had half the
state and explain how your answer to (c)(ii) wouto change
, beCG*r*%sL *k^cr- GIE"S.. \Xeseeu':*"* %
0<t\t,.*
fur\rbor**
\*l3U
o*
dutcn
C*s.c
b.o
nor^
\ec,ora
"b
er-
til
p'elto 4
ogto"* \
bace"-r-: >r'
rc-\eo''r*a b1
2[Turn over
(a)
Show ihat the unit for electrical resistivity is Om-
€n
f;= "*--
r€*
rlfr Pk
unAis
I
/,
fl_
*f1-
F
F .jznt n0
ffr.eJf- {cc ftuL.lq-
fY'\
l1l
(b)
Fig.4.1 shows a simple design for a 'movement' sensor used in an earthquake region.
The supply has negligible internal resistance.
""*o*.,
l.
Fig.4.1
A resistance wire is stretched between two rigid steel plates, not shown in the diagramDuring an earthquake, ground movement changes the separation between the plates
and so the length of wire changes.
The wire,has a radius of 0.62 mm and length 32cm. lt is made of a materialof resistivi$
6.8 x 104 Qm.
(i)
Show that the resistance of the wire is
.B
o-
6CCOP
YL::-?i
\'F-,-
+,
au\u'"
sv*cd
Ti o io'ert'dtj O
f,t \'$'r*
\' &\ i-l\tCf
= ff f Zn
ft *TrrLl
>fi r MuaF ro-t ( C'r&'t
\a) tJ
R =#F
{fi
('
1
Y\b mci-
$"
2822 JanO3
Gttr-€-f
;$.
ftfr
For
Exanine/s
&llo,o a-t#
(p'd') between A and B'
(ii) Calculate the potentialdifferYnce
P''ler*r"'t"F=';:"iA
gtt"'.J"ii'*"Ine
r=\rs-2*
t &r \Y
\' a I\F
Rr= R',
Kr:
\t
V*sr
{,-Q-
r;r
\J
: j.2V0
(iii)
\'
l-=s-o
I -r- n--
ft
ry
Use
0
= l-18L{\
* l'8fr- O
v* \.lKb x l-8
I'
1'-r-rsP"
effect on the p'd' between A
The length of the wire increases. State anO exptiin?he
and
B.
fif
: f-p-l inerca;* U;
...hrs'*n*r)*-.**rsirs*e*#*'; .Lnn,
.r
*;=t;h-""
W
tfo u; U)
it #f itr"#t.o "
'
Ac -l1l,n
r\or'
t21
[-otal: 9]
[Turn over
For
Eyaminels
Use
{ai
State ihe difference between the direciions of conventional current and electron flow-
(c
metallic conductor
Fig. 1.1a
(i)
Sketch the variation of resistance F with voltage VIor
1.
the metallic conductor at constant temperature (draw this on Fig. 1.2a)
2.
the thermistor (draw this on Fig. 1.2b).
Clur,Y!.^k, s$tqL't^
0
fi*rn r*}1g,
&-Lt ttct'3-l-
cr
\r iilL'
-G,tu-ilr
5\raV
V
Fig.
(i
i)
1.2a
i-u{
i
l,ui-
Fig- 1'2b
State and explain the change, if any, to the graph of resistance against voltage for
the metallic conductor
when the temperature of the metallic conductor is kept constant at a
1.
cY
C'*,
thermistor
metallic conductor
\hd'v^
f{
J
-I:r*.,
r
highef
\
*-....1r=..
..1."r....;,:.L.,
.
.i.t...*..\:.r.}-....,i"6...,r" ..:.,*,.. .,,.....n,i.1
, -...'i
1
j'--":1""'::"':;";{';';'E'r-"r''":'::;!""9"'Li"'t':""""'
.....-!.-'.'.:'--:s'..'....''.!'--*.---,.r.'.'.":o'..;'.,F.-.'
@, l"rt-f,
/ ....\...1j:.r...Y...:
" lt.t'-:l',*].....:......1.'......l3l-........H1...,.--...-...-.
{
/L
I
Z.
.
.;
Ft',
fi.
t.=- {.i- t ll
is doubled but the-material, temperature and
when the length-ot tn-e,
"oriOu'ctor
the cross-sectional area of the conductor remain the same.
i
*"*1b
.)
l*
'f , .
i x. *r[il
i...-.:-:.=*..-\,0....-...Y...::=-....t.-h.-'.:=-'..-.*..t.1.'....*...*C"'\.-'
n
NC;r€'.-
".....i.*...*...-,,-.....fl.......1'.:....1..:=,.:.::...3G) Wjg*,r!s-...flrltocLs:-.......
\f
, ;
i
, ; ;t.""""""'t4l
r"'.* frlcf,['. -ia'ai | ,/6'irotal:12]
i\'r/,uu'\
b-aCg+rcr
0-1
\/
[Turn over
I
,*
,1
,t
,#
i{
i!
Fig.3.1 shows the 1-Vcharacteristic of a particular electrical component.
'*
ri
l{
',*
ii
i(
ii
fi
[i'r
\--/S\rtlic,1,'rr
(
t4
'*
,#
-J
r..4.
iin* &'i''!.\
#
.;4
ii,4
CIr\5 't'
ii
:i
il
r{
,#
C'
'"'d
[r,irr.r[
t'{
ftircl''rJ
i*
'a
i4
\i
l4
1{
iA
?&,
:il
fi
1il
Fig.3"1
il
r '''.
i{
it'r
r_7
(a) Name the component.
,#
i*
'*
'4
i{
i{
(b)
Circle the correct circuit symbol for the
component.
,.*
t1l
$
tA
ii
l,i
..,i(
"4
:.1
i{
#
ia
i*
i3
(c)
Use Fig.3.1 to calculate the resistance of the component at 0.20V and 0.70V.
tt
!'J
iA
.t--.
,4
Ir
4
tt)
'n
ii
li,4
ir
il
,f4
''A.
iI
tl
t{
x
j.i'
."
{
.,,.
i""
]a
j.
'
t4
{,
it
it
it
resistance at 0.20V =
resistance at 0.70V =
/ e',[c";
i,
I
lililt ilil il|il ililt ililt
ililililt
ililt
ilil ilt ffit
:
(d)
Fig. 3.2 shows the component with the,l-Vcharacteristic shown in Fig. 3.1 connected in series
with a resistor of resistance F and a supply of e.m.f. 4.5V.
4.5V
F--l
r
0.060A
component with the 1-Y
characteristic shown in Fig.3.1
Fig.3.2
The supply has negligible internal resistance. The current in the resistor is 0.060A.
Use Fig. 3.1 to determine the resistance F of !-1e,resistor.
d-l'&(D YU-,' 4:{- -- 7S*-. @
!1-= {.s^o.js - 3,T€CI
i =o;; : lZ.it* O
o_
" O.ObO a bL"so
L o'obo
7t ^,e'5
Vd
= O'ls\r ocso*
u^*s,
a bz'So0
u)q g".lov R.= b3,a
L=
=@
(e) On the axes of Fig. 3.1 , draw the 1- V characteristic of a metallic
conductor kept at a constant
(d).
your
Label your line M.
to
answer
temperature and having the same resistance as
121
[Total:10]
'
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'9A472'1209-