jwpn 3.2

Arus mengalir kerana cas / electron
bergerak mengelilingi litar.
Electric current flows because
charges / electrons flow around a
circuit.

Apakah yang menyebabkan cas
bergerak?
What makes the electric charge to
flow?





Air daripada pili yang mengalir dari kedudukan X
ke kedudukan Y iaitu dari kedudukan yang tinggi
ke kedudukan yang rendah.
Air pada kedudukan X mempunyai tenaga
keupayaan gravity yang lebih tinggi berbanding
dengan kedudukan Y.
Perbezaan yang wujud ini menyebabkan turbin
berputar.

Water flows from position X to position Y ie from
higher position to lower position.
The pump maintains X at higher potential than Y.
The difference in potential can cause water to
flow and turns the turbine.

Titik X mempunyai keupayaan elektrik
yang lebih tinggi daripada titik Y. Hal
ini menyebabkan arus elektrik daripada
bateri mengalir dari X ke Y dan
menyalakan mentol.

Point X has higher electric potential than
point Y. This causes current from the
battery to flow from X to Y and light up
the bulb.

Buah epal akan jatuh daripada tenaga keupayaan
gravity yang lebih tinggi ke lebih rendah.
The apple movement is from high to lower
gravitational potential energy
Tenaga keupayaan graviti pada titik X lebih besar.
Gravitational potential energy at X is greater.

Ke bawah / downward

positive Negative

Tenaga keupayaan elektrik
Electric potential energy

Titik A lebih besar / point A is greater

Ini adalah disebabkan terdapat perbezaan tenaga keupayaan elektic
antara dua titik itu.
This is due to electric potential difference between the two points.

Sel kering menghasilkan medan

elektrik di sepanjang wayar logam dan

mengekalkan X pada keupayaan

elektrik yang lebih tinggi berbanding Y.

Hal ini menyebabkan arus mengalir

dari terminal positif ke terminal

negatif.

Apabila arus mengalir dari X ke Y

dalam medan elektrik tersebut, KERJA The cell creates an electrical field along
dilakukan. Ini menyebabkan tenaga the wires and maintains X at a higher
elektrik ditukarkan kepada tenaga potential than Y. This causes the
cahaya.
charges to flow. As the charges flow

from X to Y in the field, WORK is done

when electrical energy is transformed

to light and heat energy.



Beza keupayaan ialah kerja yang = joules = J C-1 = Volt = V
dilakukan apabila 1 C cas bergerak coulomb
di antara dua titik dalam medan
elektrik 1 Volt bermaksud 1 J tenaga diperlukan
untuk menggerakkan 1 C cas antara dua titik
The potential differenc, V, is dalam medan elektrik.
defined as the work done when 1 1 Volt means 1 J of energy is needed to move
C of charge moves between two 1 C of charge between two points in an
points in an electric field. electric field.

V = Kerja = Tenaga = Work = Energy
Cas cas Charge Charge

V=E
Q

√
√
√

√

V = E/Q V = E/Q
= 2.5 J = 25 J
5.0 C 5.0 C
= 0.5 J/C = 5.0 J/C
= 0.5 V = 5.0 V

E = QV = VIt
= (20)(3)(50)
= 3000 J

Ammeter

Positif

Bacaan di bawah sifar
Reading below zero.

Ampere / A
Sesiri / series



Inference:
Arus mempengaruhi kecerahan mentol
Current influence the brightness of the
bulb.

Arus mempengaruhi beza keupayaan
Current influence the potential difference

• Tujuan eksperimen/

Aim of the experiment:

Mengkaji hubungan antara arus dan
beza keupayaan untuk konduktor
Ohm.

To investigate the relationship
between current and voltage for an
ohmic conductor.

Semakin bertambah arus, semakin bertambah
beza keupayaan
The larger the current, the larger the potential
difference

Arus / current
Beza keupayaan / potential difference
Panjang konduktor / length of conductor





Berkadar terus / directly proportional

Buka suis jika tidak mengambil bacaan/
open the switch if not taking any reading

Mengawal arus yang mengalir
Control the current flows

Arus yang mengalir melalui suatu konduktor
Ohm berkadar langsung dengan beza keupayaan
yang merentasi konduktor jika suhu dan sifat
fiziknya malar.

The current flowing through an ohmic
conductor is directly proportional to the
potential difference across its ends, provided
that its temperature and the other physical
conditions remain constant.

Gradient = 1.0 V = 2.0 VA-1
0.5 A

Rintangan / resistance

Beza keupayaan,V Potential difference,V Cas melawan rintangan apabila
Arus, I Current, I mengalir melalui konduktor
Charges encounter resistance when
VA-1 = ohm = Ω R=V they flow through a conductor.
I

V = IR

V = beza keupayaan / potential difference
I = arus / current
R = rintangan / resistance

Konduktor Ohm / An ohmic conductor 

Konduktor yang mematuhi hukum Ohm
conductor which obeys Ohm’s law

Bila arus I bertambah, nisbah V/I malar

As current, I increases, the ratio V/I

is a constant

Konduktor bukan Ohm / A non ohmic
conductor 

Konduktor yang tidak mematuhi hokum
Ohm. Bila arus I bertambah, nisbah V/I
tidak malar
Conductor that does not obey Ohm’s law.
As I increase the ratio V/I is not constant

• When the voltage (V) across a piece of resistance wire is
changed, the current (I) flowing through the wire also
change. The temperature of the wire is kept constant.
Which graph shows the correct relationship between the
voltage and current?

Quiz 1

• A student wants to find the resistance of resistor R
using a voltmeter and an ammeter. Which circuit
should he use?







(a) panjang/ length / l
(b) Luas keratan rentas/ diameter
wayar / cross sectional area of
wire / diameter of wire / A
(c) Bahan wayar / material of wire

(d) Suhu / Temperature

Wayar yang digunakan dari bahan
dan ketebalan yang sama tetapi
panjang berbeza.
The wire used are of the same
material and thickness but have
different lengths.

Hitung rintangan untuk
litar A dan B
Calculate resistance for
circuit A and B.

Inferens: panjang wayar Hipotisis: semakin panjang wayar
mempengaruhi rintangan wayar semakin tinggi rintangan wayar
Inference: length of wire Hipothesis: the longer the wire
influences the resistance of wire. the higher the resistance of wire.

Panjang konduktor / Length of a conductor

Panjang konduktor berkadar terus dengan rintangan konduktor
Length of a conductor is directly proportional to its resistance.

s.w.g :
standard wire gauge

Dawai konstantan yang sama panjang
Constantan wires of the same length.
Wayar dengan swg 22 lebih tebal dari
wayar swg 30.
The wire with swg 22 is thicker than
the swg 30 wire.

Hitung rintangan untuk
litar M dan N
Calculate resistance for
circuit M and N.

Wayar swg 22 yang lebih tebal mempunyai Inferens: luas keratan rentas
rintangan lebih rendah berbanding wayar wayar mempengaruhi rintangan
swg 30. Oleh itu lebih banyak arus wayar
mengalir dalam litar N. Inference: cross sectional area of
The thicker wire of swg 22 has a lower wire influences the resistance of
resistance compared to the thinner wire of wire.
swg 30. Hence more current flows in the
circuit N.

Luas keratan rentas konduktor/ Cross sectional area of a conductor

• Semakin besar luas keratan rentas, A, satu konduktor, semakin rendah
rintangan.

• The larger the cross-sectional area, A of a conductor, the lower the
resistance.

• Rintangan berkadar songsang dengan luas keratan rentas konduktor.
• Resistance is inversely proportional to the cross-sectional area of a

conductor

Wayar sama panjang
dan tebal tetapi bahan
berbeza
Wires are of the same
length and thickness
but different materials.

Hitung rintangan untuk
litar P, Q dan R
Calculate resistance for
circuit P, Q and R.

Wayar Nikrom
mempunyai rintangan
tinggi.
Nichrome wire has high
resistance.

Wayar kuprum
mempunyai rintangan
rendah.
Copper wire has low
resistance.

Jenis bahan konduktor/ Type of material of a conductor

Rintangan konduktor berubah dengan jenis bahan konduktor.
Resistance of a conductor changes with the type of material
of the conductor.

Wayar Nikrom rintangan
tinggi.
Nichrome wire has high
resistance.
Wayar perak - rintangan
rendah.
Silver wire has low
resistance.

Suhu konduktor/ Temperature of a conductor

• Semakin bertambah suhu satu konduktor, semakin tinggi rintangan.
• The higher the temperature of a conductor, the higher the resistance.
• Rintangan berkadar terus dengan suhu konduktor.
• Resistance is directly proportional to the temperature of a conductor