Piv txwv ntawm Teeb Meem Diffraction
Kev diffraction ntawm lub teeb yog ib qho xwm txheej uas tshwm sim thaum cov nthwv dej ntawm lub teeb hla dhau qhov qhib nqaim lossis nyob ib puag ncig qhov teeb meem thiab tawg mus rau sab nraud. Qhov xwm txheej no muab pov thawj tias lub teeb muaj cov yam ntxwv nthwv dej thiab yog lub tswv yim tseem ceeb hauv physics. Hauv tsab xov xwm no, peb yuav tham txog cov piv txwv ntawm cov teeb meem diffraction ntawm lub teeb, ua tiav nrog kev sib tham thiab kev piav qhia.
Pendahuluuan
Tus kws tshawb fawb Italian Francesco Maria Grimaldi tau piav qhia txog diffraction thawj zaug hauv xyoo pua 17th. Diffraction tshwm sim thaum cov nthwv dej teeb hloov lawv txoj kev nthuav dav thaum lawv hla dhau qhov qhib lossis qhov teeb meem. Qhov no ua rau muaj tus qauv cuam tshuam ntawm diffraction. Feem ntau, diffraction pom tseeb tshaj plaws thaum qhov wavelength ntawm lub teeb sib piv rau qhov loj ntawm qhov qhib lossis qhov teeb meem uas nws hla dhau.
Qhov xwm txheej ntawm diffraction tuaj yeem piav qhia siv ob lub qauv lub cev: Wave Model thiab Geometric Optical Model. Txhawm rau xam thiab kwv yees cov qauv diffraction lub teeb, cov kab zauv diffraction tsim los ntawm Augustin-Jean Fresnel thiab Joseph von Fraunhofer feem ntau yog siv.
Lub Tswv Yim Tseem Ceeb ntawm Diffraction
Ua ntej tham txog cov teeb meem piv txwv, nws yog ib qho tseem ceeb kom nkag siab qee lub ntsiab lus yooj yim hauv kev diffraction lub teeb:
1. Ib Qho thiab Ob Chav Qhov: Tus qauv diffraction yooj yim tshaj plaws tuaj yeem pom thaum lub teeb hla dhau ib lossis ob chav qhov. Tus qauv tshwm sim yog cov kab teeb thiab tsaus ntuj ntawm lub vijtsam soj ntsuam.
2. Cov Kab Cuam Tshuam: Cov kab ci thiab cov kab tsaus ntawm lub vijtsam yog qhov tshwm sim ntawm kev cuam tshuam ntawm cov nthwv dej teeb uas raug cuam tshuam. Cov kab ci hu ua cov kab cuam tshuam tsim kho, thaum cov kab tsaus yog qhov tshwm sim ntawm kev cuam tshuam puas tsuaj.
3. Qhov Ntev Ntawm Lub Teeb: Qhov ntev ntawm lub teeb uas siv los cuam tshuam loj heev rau tus qauv diffraction. Lub teeb uas muaj qhov ntev ntawm lub teeb yuav tsim cov qauv diffraction dav dua.
4. Lub kaum sab xis diffraction: Lub kaum sab xis uas lub teeb diffraction tuaj yeem txiav txim siab siv cov ntsiab cai ntawm trigonometry thiab qhov ntev ntawm lub teeb siv.
Piv txwv ntawm Teeb Meem Diffraction
Cia peb tham txog qee qhov piv txwv ntawm cov teeb meem uas feem ntau ntsib hauv kev kawm txog lub teeb diffraction.
Piv txwv lus nug 1: Ib qho kev sib hloov ntawm qhov txiav
Lus Nug: Ib lub teeb laser nrog lub wavelength ntawm 600 nm hla dhau ib qho slit nrog qhov dav ntawm 0,2 hli. Xam lub kaum sab xis diffraction θ rau thawj qhov kev txiav txim (m = 1).
Kev Sib Tham: Hauv qhov xwm txheej ntawm ib qho kev diffraction slit, peb tuaj yeem siv cov qauv diffraction hauv qab no:
\[ a \sin \theta = m\lambda \]
Qhov twg:
- \( a \) yog qhov dav ntawm qhov sib txawv,
- \( \theta \) yog lub kaum sab xis diffraction,
- \( \lambda \) yog qhov wavelength ntawm lub teeb,
-\(m\) yog qhov kev txiav txim diffraction.
Muab:
– \( \lambda = 600 \) nm = \( 600 \times 10^{-9} \) m,
– \( a = 0.2 \) hli = \( 0.2 \times 10^{-3} \) m,
-\( m = 1\).
Hloov cov nqi rau hauv qhov sib npaug,
\[ 0.2 \times 10^{-3} \sin \theta = 1 \times 600 \times 10^{-9} \]
Kev daws rau \( \sin \theta \),
\[ \sin \theta = \frac{600 \times 10^{-9}}{0.2 \times 10^{-3}} \]
Xam \( \sin \theta \),
\[ \sin \theta = 0.003 \]
Siv lub tshuab xam zauv kom tau lub kaum sab xis \(\theta\),
\( {\theta \approx 0.172 \) degrees.
Yog li, lub kaum sab xis diffraction rau thawj qhov kev txiav txim yog li 0.172 degrees.
Piv txwv lus nug 2: Ob chav Slit Diffraction
Lus Nug: Lub teeb nrog lub wavelength ntawm 500 nm hla dhau ob lub qhov nrog qhov deb ntawm cov qhov ntawm 0,1 hli. Xam qhov chaw ntawm kab ci thib ob ntawm lub vijtsam uas yog 2 meters ntawm qhov qhov.
Kev Sib Tham: Siv cov qauv diffraction ob chav:
\[ d \sin \theta = m\lambda \]
Qhov twg:
– \( d \) yog qhov deb ntawm ob qhov sib txawv,
- \( \lambda \) yog qhov wavelength ntawm lub teeb,
-\(m\) yog qhov kev txiav txim diffraction.
Yuav nrhiav qhov chaw ntawm qhov screen (\( y \)) ntawm \( \theta \), peb siv:
\[ y = L \tan \theta \]
Rau me me \( \theta \), \( \tan \theta \approx \sin \theta \), thiab \( L \) yog qhov deb ntawm lub vijtsam los ntawm qhov slit.
Muab:
– \( \lambda = 500 \times 10^{-9} \) m,
– \( d = 0.1 \times 10^{-3} \) m,
– \( L = 2 \) m,
-\( m = 2\).
Hloov cov nqi rau hauv qhov sib npaug,
\[ 0.1 \times 10^{-3} \sin \theta = 2 \times 500 \times 10^{-9} \]
Kev daws rau \( \sin \theta \),
\[ \sin \theta = \frac{1000 \times 10^{-9}}{0.1 \times 10^{-3}} \]
Xam \( \sin \theta \),
\[ \sin \theta = 0.01 \]
Xav tias \( \sin \theta = \tan \theta \) rau qhov deb loj, thiab hloov rau hauv qhov sib npaug ntawm qhov chaw,
\[ y = 2 \times 0.01 = 0.02 \] m los yog 20 hli.
Yog li, qhov chaw ntawm kab ci thib ob ntawm qhov screen yog 20 hli ntawm qhov chaw nruab nrab ntawm qhov screen.
Kev kaw
Kev diffraction ntawm lub teeb yog ib qho kev kawm uas qhia tau tias lub teeb ua haujlwm zoo li nthwv dej. Qhov xwm txheej no muab cov ntawv thov tseem ceeb hauv ntau qhov kev tshawb fawb, tshwj xeeb tshaj yog optics thiab spectroscopy. Kev nkag siab txog diffraction tsis yog raws li kev xav xwb tab sis kuj los ntawm kev daws ntau yam teeb meem uas tuaj yeem pab kom nkag siab tob txog cov yam ntxwv nthwv dej ntawm lub teeb.
Nrog kev nce qib hauv thev naus laus zis rau kev soj ntsuam thiab nkag siab txog cov yam ntxwv ntawm lub teeb, qhov tshwm sim ntawm diffraction tseem siv tau rau ntau yam kev tshawb pom tshiab thiab kev siv thev naus laus zis, los ntawm telescopes mus rau cov cuab yeej ntsuas siab. Yog li ntawd, kev kawm diffraction tsis yog tsuas yog kev txaus siab rau kev kawm xwb tab sis kuj muaj cov txiaj ntsig zoo rau lub neej txhua hnub thiab kev txhim kho thev naus laus zis.
