1
PHYSICS
MODULE
2. ELECTRICITY
TOPIC:
2 ELECTRICITY
2.2 ANALYSING THE RELATIONSHIP BETWEEN
ELECTRIC CURRENT AND POTENTIAL
DIFFERENT
CONTENTS:
1. CHAPTER HIGHLIGHT (30 MINUTES)
2. ACTIVITY (50 MINUTES)
3. ASSESSMENT (0 MINUTES)
. MAR!ING SCHEME(ANSWER !EY)
2
CHAPTER 2
ELECTRICITY
2.2 Analysing the relationship between electric current and potential dierence
1. ____________________ is an area where the electric force is acting.
2. If a positive test charge is located at a point A within the electric field, this charge will be
________________ by the electric field outwardly through a point B.
3. This positive test charge oves because of the e!istence of the electric
__________________________ between point A and B.
". If the positive test charge is oved fro point B to point A, the wor! is done to oppose the
electric force.
#. Potential dierence or "oltage# $ between A and B is defined as the ________________ to
ove a unit charge fro B to A within an electric field.
3
Positi"e test charge
A %
Potential dierence & 'or! done
($oltage) Charge
$ & '
*
Unit: $ & + & +C
,-
C
.
.
/. 0h12s Law states that the current, I flows through an electric conductor is
__________________________ to the potential difference, $ across two ends of the conductor,
with the conditions that the teperature and the physical state of the conductor do not change.
%. A conductor which produces graph $&I with a straight line passing through the origin of the
graph is said obeys 'h(s )aw and is *nown as an ___________ conductor. Those which do
not have such characteristic are *nown as _________________ conductor.
V (V)
I (A)
+. _________________ of a conductor can be defined as the ratio of the potential difference, $
across that conductor to the current, I which flows through it.
"
$ I
R & $
I
Unit: 3 & $A
,-
(oh1)
,. -raphs of 'hic conductor and non&'hic conductors.
Ohmic conductor
(a) Standard resistor
I
V
(b) Standard resistor (Eureka/Wolfrum,
Cuprum (II) Sulfate ith Cuprum electrod)
I
V
!on"Ohmic conductor
(c) #as under lo
pressure
I
V
(d) $ilute Sulfuric
acid ith Carbon
electrod
I
%&' V
(e) Vacuum diode
tube, therma diode,
photo cell
I
V
(f) (ulb
I
V
1.. /actors which influence the conductor resistance.
#
Resistance & Resisti"ity 4 length
Area
R & 5 4 l
A
Unit: 3 & 3 1 4 1
1
2
6actors7
-. Type o
1aterial# 5
2. Length#
8. Cross section
area# A
9. Te1perature#
11. Analysing the factors which influence the conductor resistance.
The circuit:
)AC*O+ ,E!#*-, . C+OSS
SEC*IO! A+EA,
A
/A*E+IA,
*01E, 0
(+ESIS*IVI*0)
*E/1E+A*2+E
3
#raph +/ 1
./cm
+/ 1
thin
mod&
thick
./cm
+/ 1
!i
W
Cu
./cm
+/ 1
3/
o
C
V/V
I/A
+elationship R R -
A
R s.w.g.
R 5
R increases
linearly with
/anipulated ,en4th of ire Cross section of
the ire
*5pe of
material
*emperature of
filament
+espondin4 +esistance, +
Or 6olta4e, V
+esistance, +
Or 6olta4e, V
+esistance, +
Or 6olta4e, V
+esistance, +
Or 6olta4e, V
Constant C&S& Area, A
*5pe of material
(+esisti6it5 , 02
Teperature, 3
Current, I
,en4th, .
*5pe of material
(+esisti6it5 , 02
Teperature,3
Current, I
C&S& Area, A
,en4th, .
Teperature,3
Current, I
C&S& Area, A
*5pe of material
(+esisti6it5 , 02
,en4th, .
Current, I
!ote Current, I is
kept constant
*hin7s4 89
/od&7s4 :;
*hick7s4 ::
!i7!icrom
W7Wolferum/
Eureka/Const&
Cu7Cuprum
*emperature of
filament rep& b5
*he bri4htness
of the bulb
3
A
$
12. ___________________ is the conductor with 4ero resistance when it is cooled below the
critical teperature, Tc.
13. If the current is produced in the superconductor coil, the current will continuously flow
without causing the lost of energy even though the electric source is terinated.
1". 5oparison of the graphs of different conductivity
Conductor ire Semiconductor Superconductor
+/ 1
3/
o
C
+/ 1
3/
o
C
+/ 1
*
c
3/
o
C
1#. The usage of superconductor
!o )ield E<plaination
% Electronic circuit board Superconductor coil in the 4enerator, motor
and transformer makes the appliances
become smaller in si=e but poerfull5
perform
: Electrical Ener45 Suppl5 Superconductor cable ith =ero resistance
increases the efficienc5 of suppl5in4 the
ener45 because the lost of ener45 in the
form of heat does not occur
8 *ransportation >)loatin4? bullet train ith hi4h speed (@@9
kmh
"%
) is introduced b5 consumin4 a 6er5
stron4 superconductor ma4net
; /edicine Scannin4 technic such as /+I (/a4netic
+esonance Ima4in4) is introduced to
replace A"ra5& *his technic 4enerates a 6er5
stron4 ma4netic field from the
superconductor coil
@ Computer Computer chips are performin4 at faster rate
and smaller si=e of the chips can be
produced
%
Asses1ent
0b:ecti"e ;uestions
1. The following stateents about the electric current are true e!cept
A 6lectric current is proportional to the rate flow of charge
B The current through a conductor is proportional to the potential different across it
5 The current generate heat effect dan agnet effect
7 The electric current can be produced only by the flow of electron
2. 8hat will happen to the resistance of a wire if both the length and the diaeter of the wire are
double 9
A :esistance does not change
B :esistance reduced to one forth
5 :esistance reduced to a half
7 :esistance increases two ties higher
<tructured *uestions
A. 1 7efine the following ters.
;a2 <otential different=
__________________________________________________
__________________________________________________
;b2 :esistance= __________________________________________________
__________________________________________________
+
Potential difference or voltage, V beteen A and ( is defined as the ork done
to mo6e a unit char4e from ( to A ithin an electric field&
Resistance, R of a conductor can be defined as the ratio of the potential
difference, V across that conductor to the current, I hich flos throu4h it&
2 >*etch the circuit which can be used to analyse the factors which influence the conductor
resistance.
3. )ist the factors which influence the conductor resistance.
B 1. )ist and e!plain three of the uses of superconductor
,
Answer= 1 7 2 5
1.
