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MODUL • Fizik TINGKATAN 5

Dari graf di atas, dan dari V = -rI + E, iaitu
From the graph above, and from V = -rI + E, that is

Apabila / When I = 0 A,
Pengiraan V = E (dalam Volt / in Volt)
Calculations Maklumat tambahan:
Kecerunan graf / Gradient of the graph = – r Additional information:
\ r = – kecerunan graf (dalam Ω)
r = – gradient of the graph (in Ω)

Latihan / Exercise

1 Rajah menunjukkan satu litar elektrik. Apakah rintangan dalam bateri?
The diagram shows an electrical circuit. What is the internal resistance of the battery?
Penyelesaian / Solution
S
Diberi / given E = 1.5 V, V = 1.0 V, R = 5 Ω
V R V
Arus / Current, I = R
1.0 V UNIT 2
A = 5 Ω = 0.2 A
UNIT 2
Apabila suis S dibuka, bacaan voltmeter ialah
1.5 V. Apabila suis S ditutup bacaan voltmeter dan ammeter E = V + Ir
ialah 1.35 V dan 0.3 A masing-masing. 1.5 V = 1.0 V + (0.2 A) r
When the switch S is open, the reading of the voltmeter is r = (1.5 – 1.0) V
1.5 V. When the switch S is closed the reading of the voltmeter 0.2 A
and ammeter are 1.35 V and 0.3 A respectively. = 2.5 Ω
Tentukan / Determine
(a) daya gerak elektrik pada sel 3 Graf menunjukkan perubahan beza keupayaan dengan
the e.m.f. of the cell arus bagi sebuah bateri.
(b) rintangan dalam sel The graph shows the variation of potential difference with
the internal resistance of the cell KBAT current of the battery.
(c) rintangan R V / V
the resistance R
Penyelesaian / Solution
3.0
(a) E = 1.5 V (c) V = IR
(b) E = V + Ir 1.35 V = (0.3 A)R 1.7
1.5 V = 1.35 V + (0.3 A)r 1.35 V
(0.3 A) r = (1.5 – 1.35)V R = 0.3 A I / A
0.15 V R = 4.5 Ω 0 0.74
r =
0.3 A
= 0.5 Ω Berdasarkan graf, tentukan rintangan dalam pada bateri.
From the graph, determine the internal resistance of the
2 Daya gerak elektrik, E, pada bateri ialah 1.5 V. Bateri ini battery.
disambungkan kepada perintang 5 Ω. Apabila litar ditutup, Penyelesaian / Solution
bacaan voltmeter ialah 1.0 V. Apabila nilai I = 0, didapati V = E.
KBAT
The e.m.f., E of a battery is 1.5 V. This battery is connected When the value of I = 0, V = E is obtained.
to a 5 Ω resistor. When the circuit is closed, the reading
of the voltmeter is 1.0 V. Daripada graf, E = 3.0 V
From the graph, E = 3.0 V
V Maka, rintangan dalam, r
E = 1.5 V Hence, the internal resistance, r = E – V
I
(3.0 – 1.7) V
= 0.74 A
R = 5 Ω
= 1.76 Ω

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