Interferensi Celah Ganda dan Kisi Difraksi
| English | Bahasa Indonesia |
|---|---|
| diffraction grating/dɪˈfrækʃn ˈɡreɪtɪŋ/ | kisi difraksi |
Shine light through two slits — and get stripes, not two lines
- Send light through two narrow slits and the screen shows a row of bright and dark stripes.
- Not two bright lines as you'd expect — an interference pattern.
- This is Young's double-slit experiment, and it proved light is a wave.
- The same idea, with thousands of slits, becomes a diffraction grating.
How the fringes form
- Light spreads (diffracts) from each slit, and the two sets of waves overlap and interfere.
- Where they arrive in phase, they add — a bright fringe.
- Where they arrive out of phase, they cancel — a dark fringe.
- The pattern is a direct picture of constructive and destructive interference.
Dua gelombang yang saling berinterferensi
Ubah perbedaan fase dan lihat dua gelombang bertambah menjadi terang (sefase) atau saling meniadakan menjadi gelap (tidak sefase).
Pola interferensi celah ganda adalah bukti bahwa cahaya adalah:
Interferensi adalah fenomena gelombang, jadi garis-garis membuktikan cahaya adalah gelombang.
The bright-fringe condition
- Bright fringes appear where the path difference from the two slits is a whole number of wavelengths.
- The condition is $d\sin\theta = m\lambda$, with $m = 0, 1, 2, \ldots$
- Closer slits (smaller $d$) or a longer wavelength spread the fringes further apart.
- Measuring the fringe spacing lets you calculate the wavelength of the light.
Garis terang terbentuk di mana selisih lintasan dari kedua celah adalah:
Garis terang memerlukan $d\sin\theta = m\lambda$ — kelipatan bulat dari panjang gelombang.
Jika jarak pisah celah $d$ dikurangi setengahnya, jarak antar garis:
Jarak garis berbanding lurus dengan $1/d$, sehingga mengurangi setengah $d$ menggandakan jarak.
Garis gelap terbentuk di mana gelombang dari kedua celah tiba tidak sefase dan saling meniadakan.
Kedatangan tidak sefase menyebabkan interferensi destruktif — garis gelap.
Diffraction gratings
- A diffraction grating 衍射光栅 has thousands of fine slits packed together.
- It splits light into very sharp, bright spots — far cleaner than two slits.
- It also spreads different colours by different angles, making a spectrum.
- Gratings are used in spectrometers to identify the elements in stars and samples.
Perangkat dengan ribuan celah halus yang memecah cahaya menjadi titik-titik tajam adalah kisi difraksi ____.
Kisi difraksi memberikan maksimum yang sangat tajam dan terang.
Pilih semua pernyataan benar tentang celah ganda dan kisi.
Terang = selisih lintasan kelipatan bulat; interferensi membuktikan cahaya adalah gelombang; kisi menghasilkan spektrum. Pola ini adalah interferensi, bukan senter independen.
The double-slit fringes come from interference, not from the slits acting as tiny torches — that's why you get a pattern of stripes, not two bright bars. Bright fringes need a path difference of a whole number of wavelengths ($d\sin\theta = m\lambda$); half-wavelengths give dark fringes.
In a double-slit setup, the slit separation is halved. What happens to the fringe spacing?
- Fringe spacing goes as $1/d$, so halving $d$ doubles the spacing.
- The bright stripes move further apart on the screen.
Young's double slit makes bright and dark fringes by interference — bright where $d\sin\theta = m\lambda$ (whole-number path difference). Closer slits or longer wavelengths spread the fringes wider. A diffraction grating (thousands of slits) gives sharp spots and splits light into a spectrum.