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h
–28
2. Jika momentum foton adalah 3.4 × 10 kg m s , ρ = —
–1
hitungkan panjang gelombang. λ –34
(6.63 × 10 )
–1
8
[Anggarkan h = 6.63 × 10 –34 J ; c = 3.00 × 10 m s ] λ = ——————
If the momentum of a photon is 3.4 × 10 kg m s , what 3.4 × 10 –28
-1
–28
–6
is the wavelength? λ = 1.95 × 10 m
[Assume h = 6.63 × 10 J s; c = 3.00 × 10 m s ]
–34
8
-1
hc
(6.63 × 10 )(3.0 × 10 )
8
–34
3. Sinar laser mempunyai 7.0 mW dengan E = —– = ——————————
menggunakan electromagnet panjang gelombang λ 650 × 10 –9
650 nm. Kirakan bilangan foton yang dihasilkan E = 3.1 × 10 J
–19
setiap saat. hc
The laser beam has 7.0 mW using a 650 nm wavelength P = n1 —–2 = nhf
λ
P
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electromagnet. Calculate the number of photons per n = —–
second. hf
7 × 10 –3
n = ———–—
3.1 × 10 –19
= 2.3 × 10 s –1
16
4. Sinar laser dipancarkan ke atas kepingan logam (a) E = hf
dengan luas keratan rentas, 2.0 × 10 m dan kuasa E = (6.63 × 10 )(4.3 × 10 )
–34
2
14
–4
4.5 mW. Jika frekuensi gelombangnya adalah E = 2.9 × 10 J
–19
P
4.3 × 10 Hz, hitungkan n = —–
14
The laser beam is directed to a sheet of metal with a cross hf
sectional area, 2.0 × 10 m and 4.5 mW of power. If the 4.5 × 10 –3
-4
2
wavelength is 4.3 × 10 Hz, calculate n = —————
14
2.9 × 10
–19
KBAT Menganalisis n = 1.6 × 10 s –1
16
(a) bilangan foton yang terkena permukaan logam (b) Gelombang bersifat zarah, momentum, p
dalam 1 saat. Wave behave as a particle, momentum, p
number of photons exposed to metal surfaces in 1 h
second. ρ = — untuk satu foton/ for one photon
λ
(b) perubahan momentum bagi foton
the change in momentum for the photons Jumlah perubahan momentum
Total change in photons momentum
h
ρ = n—
λ
(1.6 × 10 )(6.63 × 10 )
–34
16
ρ = ——————————
7.0 × 10 –7
ρ = 1.5 × 10 kg m s –1
–11
7.2 Kesan Fotoelektrik Buku Teks
Photoelectric Effect m.s. 234-237
Nota
1. Pada tahun 1887, Heinrich Hertz menemui kesan fotoelektrik melalui eksperimen sinaran gelombang
elektromagnet ke atas plat logam. Pada tahun 1897, J.J. Thomson mempertingkatkan lagi kesan
fotoelektrik.
In 1887, Heinrich Hertz discovered a photoelectric effect by electromagnetic radiation experiments on metal plates.
In 1897, J.J. Thomson reiterated the photoelectric effect.
2. Kesan fotoelektrik merujuk kepada fenomena pengeluaran elektron dari permukaan logam apabila ianya
disinari dengan gelombang elektromagnet.
The photoelectric effect refers to the phenomenon of electron emission from a metal surface when it is illuminated
by an electromagnetic wave.
3. Berdasarkan teori gelombang/ Based on the wave theory:
• Tenaga kinetik bagi elektron yang dibebaskan bergantung kepada keamatan sinar gelombang
The kinetic energy of the released electrons depending on the intensity of the beam

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