Rajah 9.1 dan 9.2
menunjukkan sinar cahaya selari yang ditujukan ke arah
cermin cembung P dan
Q. F adalah titik fokus bagi setiap cermin tersebut.
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(a)
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What is the focal length of a convex mirror?
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Apakah panjang fokus bagi
suatu cermin cembung?
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[1 mark / markah]
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(b)
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Referring to the above diagram, compare the curve of the mirror and
the way the rays are bend on passing through the mirror. State the
relationship between the curve of the mirror and its focal length.
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Merujuk kepada gambarajah
di atas,bandingkan bentuk cermin dan bengkokan sinaran cahaya selepas melalui
cermin tersebut. Nyatakan hubungan di antara bentuk cermin dengan panjang
fokus.
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[4 marks / markah]
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(c)
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You are given one convex mirror, one concave mirror and a bulb (as
the source of light ray).
With aid of a suitable ray diagram, choose any two
of the materials and arrange them
to produce a parallel light ray.
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Anda di beri satu cermin
cembung, satu cermin cekung dan mentol
(sebagai sumber cahaya). Dengan
bantuam gambarajah sinar, pilih
dua dari bahan dan susun keduanya untuk
menghasilkan cahaya selari.
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[5marks / markah]
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(d)
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shows the use of mirror in our daily life.
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Encik Ahmad wants to put up a mirror so that he can watch over his
customer,
especially the shoplifter in his supermarket. Explain the
suitability of the mirror
he chooses. In your explanation, state clearly
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Encik Ahmad ingin
meletakkan cermin untuk memerhatikan pelanggannya
terutama pencuri di
supermarketnya. Terangkan cermin yang sesuai
digunakan. Dalam penerangan
anda, nyatakan dengan jelas
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(i)
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the type of
the mirror,
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jenis cermin
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(ii)
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the size of
the mirror,
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saiz cermin
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(iii)
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the location
of the mirror.
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kedudukan cermin
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[6 marks / markah]
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The same
type of mirror is also being use elsewhere in our daily lives.
Name two other
places where the mirror is being used and explain why.
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Jenis cermin yang sama
juga digunakan dalam keadaan lain dalam
kehidupan harian. Namakan dua tempat
di mana cermin tersebut
digunakan dan jelaskan mengapa.
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[4 marks / markah]
Supply 9 Joule electric energy
for each coulomb of charge transfer from one point to another point within a
material
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Electrical energy à
Light energy + Heat energy
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Diagram
4.2 is brighter // Diagram 4.1 is dimmer
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The
brighter bulb has larger amount of current //
The
dimmer bulb has smaller amount of current
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The
brighter the bulb , the higher the current flows
and
Internal
resistance of dry cell is lower //otherwise
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Lead-acid accumulator
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No
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8 dry cells are arranged in
serial so the total internal resistance is
8 x 0.5 = 4 Ω
Current flow, I = V/R = 12/4 = 3
A
This small current cannot start
the engine.
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Modification
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Explanation
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Use the fluorescent lamp
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Consume less power and economic
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Use a more efficient
fluorescent lamp
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It brightens the room more
clearly and thoroughly and prevents wastage
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Use a more energy efficient
fluorescent lamp
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Helps the temperature in the
room to be not too hot due to less energy loss in form of heat energy.
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Fuses should be connected to
the fluorescent lamp
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To prevent overheating of lamps
might cause the fluorescent lamp to blow out.
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Two or more fluorescent lamp
are arrange in parallel.
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If one lamp blows the rest are
still functioning.
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