Kev txhais ntawm lub iav loj
nyiag los yog ib lub iav loj yooj yim los yog iav loj yog lub lens convex uas yog siv los pab lub qhov muag pom ib yam khoom uas nyuaj rau pom ncaj qha nrog lub qhov muag, piv txwv li cov ntawv sau me me heev. Lub iav tsom iav hu ua lub iav tsom iav yooj yim vim nws muaj peev xwm txwv tsis pub ua kom daim duab ntawm ib yam khoom loj dua. Hauv zaj lus qhia tom ntej, koj yuav kawm txog lub iav tsom iav uas tsis yooj yim xws li tshuab raj, lub tsom iav hauv av dan lub tsom iav.
Lub Magnifier Ua Haujlwm Li Cas
Thaum pom ntawm qhov deb ze, ib yam khoom zoo li loj, tab sis thaum pom ntawm qhov deb heev, yam khoom zoo li me. Cov khoom ze zoo li loj vim tias qhov loj ntawm daim duab uas tsim rau ntawm retina loj. Ntawm qhov tod tes, tib yam khoom thaum pom ntawm qhov deb heev zoo li me vim tias qhov loj ntawm daim duab uas tsim rau ntawm retina me. Yog li, qhov loj ntawm ib yam khoom uas pom los ntawm lub qhov muag nyob ntawm qhov loj ntawm daim duab uas tsim rau ntawm retina. Qhov loj ntawm daim duab uas tsim rau ntawm retina nyob ntawm lub kaum sab xis uas tsim ntawm lub qhov muag thiab yam khoom, raws li pom hauv daim duab hauv qab no.
Cov khoom uas nyob deb ntawm lub qhov muag zoo li me dua vim lawv muaj lub kaum sab xis me dua (θ) (Daim Duab 1.1). Ntawm qhov tod tes, cov khoom uas nyob ze rau lub qhov muag zoo li loj dua vim lawv muaj lub kaum sab xis loj dua (θ) (Daim Duab 1.2). Nws tuaj yeem xaus lus tias qhov loj ntawm ib yam khoom uas lub qhov muag pom tuaj yeem ua kom loj dua lossis txo qis los ntawm kev nce lossis txo lub kaum sab xis (θ). Lub kaum sab xis raug ua kom loj dua los ntawm kev coj lub qhov muag los ze rau yam khoom, ntawm qhov tod tes lub kaum sab xis raug txo qis los ntawm kev txav lub qhov muag tawm ntawm yam khoom.
Cov lus sib tham saum toj no siv tau rau lwm yam teeb meem. Yog tias koj ntsib cov ntawv sau me me uas nyuaj nyeem, koj yuav ua li cas kom nyeem tau yooj yim? Raws li cov lus sib tham saum toj no, koj yuav coj cov ntawv los ze rau koj lub qhov muag kom nce lub kaum sab xis ntawm cov ntawv thiab koj lub qhov muag, ua rau cov ntawv loj dua thiab nyeem tau yooj yim dua. Nws yog ib qho tseem ceeb kom paub tias ze ntawm qhov muag ib txwm muaj los yog qhov deb tshaj plaws uas lub qhov muag ib txwm tuaj yeem tsom mus rau yog 25 cm, yog li ntawd yog tias qhov deb ntawm qhov sau ntawv thiab lub qhov muag me dua 25 cm, cov ntawv sau yuav zoo li tsis meej. Cov ntawv sau uas nyeem tau ntawm qhov deb ntawm 25 cm yuav zoo li tsis meej thaum coj los ze dua kom txog thaum qhov deb ntawm qhov sau ntawv thiab lub qhov muag me dua 25 cm, tsis txhob hais txog cov ntawv sau uas nyeem tsis tau ntawm qhov deb ntawm 25 cm? Yog li koj yuav ua li cas kom cov ntawv sau uas muaj cov ntawv me me nyeem tau yooj yim? Tau kawg, koj xav tau kev pab los ntawm lub cuab yeej kho qhov muag uas tuaj yeem ua kom cov ntawv sau loj dua.
Cov cuab yeej siv kho qhov muag xws li daim iav tiaj tus, daim iav concave dan daim iav convex siv tsis tau los nyeem cov ntawv sau vim daim iav tsis pob tshab. Ntawm qhov tod tes, lub lens pob tshab yog li nws siv tau los nyeem cov ntawv sau. Hauv zaj lus qhia duab lens concave, nws piav qhia tias lub lens concave tsuas yog txo tau cov duab ntawm ib yam khoom. Nyob rau hauv sib piv, nyob rau hauv lub ncauj lus duab lens convex Piav qhia tias lub lens convex tuaj yeem ua kom daim duab ntawm ib yam khoom loj dua. Vim tias nws tuaj yeem ua kom daim duab loj dua, lub lens convex tuaj yeem tsim los ua lub iav loj.
Saib ob daim duab hauv qab no. Hauv Daim Duab 1.3, lub qhov muag pom qhov khoom ncaj qha, qhov twg qhov khoom zoo li me me vim tias lub kaum sab xis ntawm lub qhov muag thiab ob sab kawg ntawm qhov khoom me me. Hauv Daim Duab 1.4, lub qhov muag saib qhov khoom los ntawm lub iav tsom iav. Lub iav tsom iav ua haujlwm los tsim ib daim duab thiab ua kom daim duab ntawd loj dua, yog li qhov muag pom yog daim duab. Daim duab ntawm qhov khoom uas lub qhov muag pom los ntawm lub iav tsom iav zoo li loj dua vim tias lub kaum sab xis ntawm lub qhov muag thiab ob sab kawg ntawm daim duab loj dua.
Yuav kom tus neeg saib lub qhov muag pom tau daim duab los ntawm lub iav tsom iav, daim duab yuav tsum yog virtual (daim duab nyob rau pem hauv ntej ntawm lub iav tsom iav lossis daim duab nyob rau tib sab ntawm yam khoom, zoo li hauv daim duab 1.4). Txog lub ncauj lus duab lens convex Nws tau piav qhia tias rau daim duab kom ua virtual, qhov deb ntawm cov khoom yuav tsum me dua lossis sib npaug rau qhov ntev ntawm lub focal (f).
Cov Lus Piav Qhia:
s = qhov deb ntawm yam khoom
s' = qhov deb ntawm daim duab
h = qhov siab ntawm yam khoom
h' = qhov siab ntawm qhov ntxoov ntxoo
F = qhov chaw tseem ceeb ntawm lub iav tsom iav
θ = lub kaum sab xis ntawm lub lens thiab ob sab kawg ntawm yam khoom. Hauv Daim Duab 1.3, lub lens uas hais txog yog lub qhov muag, thaum nyob hauv Daim Duab 1.4, lub lens uas hais txog yog lub lens convex uas siv ua lub iav loj.
Hauv Daim Duab 1.3 (saib sab), yam khoom nyob rau sab laug thaum tus neeg saib lub qhov muag nyob rau sab xis. Hauv Daim Duab 1.4 (saib sab), yam khoom thiab nws cov duab uas tsim los ntawm lub lens convex nyob rau sab laug thaum tus neeg saib lub qhov muag nyob rau sab xis.
Yuav Siv Lub Tshuab Loj Li Cas
Thaum qhov deb ntawm yam khoom (s) zoo ib yam li qhov ntev ntawm lub focal (f), daim duab yog virtual thiab qhov deb ntawm daim duab (s') yog infinite. Infinity yog qhov deb ntawm daim duab virtual siab tshaj plaws vim tias qhov deb Qhov deb ntawm lub qhov muag ib txwm yog qhov tsis kawg. Ntawm qhov tod tes, qhov deb ntawm daim duab virtual tsawg kawg nkaus yog 25 cm vim tias ze ntawm qhov chaw qhov muag ib txwm yog 25 cm.
Thaum lub qhov muag saib ib daim duab virtual ntawm qhov tsis kawg (qhov deb), lub qhov muag nyob rau qhov tsawg kawg nkaus, lossis cov leeg nqaij ciliary so tshaj plaws. Yuav kom ua tiav qhov no, qhov deb ntawm yam khoom thiab lub iav tsom iav yuav tsum sib npaug rau qhov ntev ntawm lub iav tsom iav. Yog tias qhov ntev ntawm lub iav tsom iav yog 25 cm, ces qhov deb ntawm yam khoom thiab lub iav tsom iav yog 25 cm.
Ntawm qhov tod tes, thaum lub qhov muag pom ib daim duab virtual ntawm qhov deb ntawm 25 cm (qhov ze), lub qhov muag yuav haum rau qhov siab tshaj plaws lossis cov leeg nqaij ciliary ntawm lub qhov muag nyob rau hauv qhov xwm txheej nruj tshaj plaws. Yog tias qhov ntev ntawm lub iav tsom iav yog 25 cm, ces lub qhov muag pom ib daim duab virtual ntawm qhov deb ntawm 25 cm thaum qhov deb ntawm yam khoom yog tib yam li qhov tshwm sim xam hauv qab no.
Cov qauv ntawm lub lens nkhaus thiab daim iav:
1/s = 1/f – 1/s'
Kev piav qhia: s = qhov deb ntawm yam khoom, f = qhov ntev ntawm lub zeem muag, s' = qhov deb ntawm daim duab = qhov ze = 25 cm
Lub iav tsom iav yog lub lens convex, yog li qhov ntev ntawm lub lens yog positive. Daim duab yog virtual, yog li s' yog negative.
1/s = 1/f – (-1/s') = 1/f + 1/s'
1/s = 1/25 + 1/25 = 2/25
s = 25/2 = 12,5 cm
Yog tias qhov deb ntawm lub loupe yog 25 cm, lub qhov muag pom ib daim duab virtual ntawm qhov deb ntawm 25 cm thaum qhov deb ntawm yam khoom yog 12,5 cm. Qhov deb ntawm yam khoom thiab lub loupe yuav tsum tsis txhob me dua 12,5 cm vim tias daim duab uas lub loupe tsim tawm tsis tuaj yeem pom tseeb los ntawm lub qhov muag.
Yog tias qhov ntev ntawm lub iav tsom iav yog 50 cm, ces lub qhov muag pom ib daim duab virtual ntawm qhov deb ntawm 25 cm thaum qhov deb ntawm yam khoom zoo ib yam li qhov tshwm sim hauv qab no.
1/s = 1/f – (-1/s') = 1/f + 1/s'
1/s = 1/50 + 1/25 = 1/50 + 2/50 = 3/50
s = 50/3 = 16,67 cm
Yog tias qhov deb ntawm lub loupe yog 50 cm, lub qhov muag pom ib daim duab virtual ntawm qhov deb ntawm 25 cm thaum qhov deb ntawm yam khoom yog 16,7 cm. Qhov deb ntawm yam khoom thiab lub loupe yuav tsum tsis txhob me dua 16,7 cm vim tias daim duab uas lub loupe tsim tawm tsis tuaj yeem pom tseeb los ntawm lub qhov muag.
Kev Ua Kom Loj Hlob ntawm Lub Iav Loj Hlob
Daim duab ntawm ib yam khoom uas pom los ntawm lub iav tsom iav puas loj dua thaum lub qhov muag uas muaj qhov chaw me me lossis lub qhov muag uas muaj qhov chaw loj tshaj plaws? Qhov twg zoo dua los siv ua lub iav tsom iav, lub lens convex nrog qhov ntev focal loj lossis lub lens convex nrog qhov ntev focal me? Cov lus nug no tuaj yeem teb tau tom qab koj kawm cov qauv iav loj.
