Izibonelo Eziyi-8 Zemibuzo Ephelele Yezinkinga Zamehlo
1. Indlela yokukhanya ekhombisa ukwakheka kwesithombe ngelensi yeso lomuntu onesifo se-myopic iboniswe esithombeni...
Ingxoxo
Ukubuka kude noma myopia Ukubona kude kuyisifo sokubona iso lapho iso lingakwazi ukubona kahle amaphuzu akude. Ukubona kude yibanga elide kakhulu iso elivamile elingalibona kahle. Umuntu ojwayelekile onamehlo ajwayelekile unokubona kude okungapheli.
Imbangela yokungaboni kahle yisimiso se-cornea-lens esigobile kakhulu (ingxenye evundlile yeso inde kakhulu) ukuze ubude bokugxila besistimu ye-cornea-lens buncishiswe, okubangela ukuthi imisebe yokukhanya evela endaweni ekude igxile phambi kwe-retina. Imisebe yokukhanya engenamkhawulo ayigxilile ku-retina ukuze amangqamuzana ezinzwa ku-retina angakwazi ukuguqula amaza okukhanya abe izimpawu zikagesi ezizodluliselwa ebuchosheni.
Impendulo efanele ngu-A.
2. U-Ani unesifo sokubona kakhulu, isimo esibangelwa…
A. Iphuzu elikude leso lisondela eduze kweso
B. Iphuzu elikude leso liyasuka esweni
C. Iphuzu eliseduze kweso lisondela esweni.
D. indawo eseduze kweso iyasuka esweni
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Ukubuka kude noma hyperopia kuyinto engavamile izinsimbi zokukhanya lapho iso lingakwazi ukubona iphuzu eliseduze ngokucacile noma iphuzu eliseduze libonakala lifiphele. Iphuzu eliseduze yibanga eliseduze kakhulu iso elivamile elingalibona ngokucacile. Umuntu ojwayelekile onamehlo ajwayelekile unephuzu eliseduze elingama-25 cm. Abantu abanokubona kude bangabona iphuzu elikude ngokucacile, ngakho-ke kungashiwo ukuthi lokhu kwenzeka. i-hyperopia, indawo eseduze kweso iyasuka esweni.
Impendulo efanele ngu-D.
3. Bheka isithombe!
Yiziphi izinhlobo zeziphambeko zamehlo nezibuko ezingasiza abagulayo ngalezi zibuko?
A. Ukubona izinto kude kanye ilensi eqondile
B. Ukubona izinto kude kanye ilensi egobile
C. Ukubona eduze namalensi acwebezelayo
D. Ukubona eduze namalensi aqondile
Ingxoxo
Izinkinga zamehlo esithombeni esingenhla yilezi: ukubona eduze noma i-myopia, seindlela umdwebo wendlela yemisebe oboniswa ngayo esithombeni ohlangothini.
Ukubona eduze kuyisifo sokubona iso lapho izinto ezikude zibonakala zifiphele khona. Iphuzu elikude yibanga elide kakhulu iso elivamile elingalibona kahle. Umuntu ojwayelekile onamehlo ajwayelekile unephuzu elingapheli.
Imbangela yokungaboni kahle yisistimu yelensi ye-cornea egobile kakhulu (ingxenye evundlile yeso inde kakhulu) ukuze ubude bokugxila besistimu yelensi ye-cornea buncishiswe, okubangela ukuthi imisebe yokukhanya evela ezindaweni ezikude igxile phambi kwe-retina. Imisebe yokukhanya ayigxilile ku-retina ukuze amangqamuzana ezinzwa ku-retina angakwazi ukushintsha indlela yokukhanya. 
Lawa maza okukhanya aba izimpawu zikagesi ezidluliselwa ebuchosheni.
Ukukhanya kungagxila ngqo ku-retina uma kubekwe endaweni efanele ilensi egobile phambi kweso. Ilensi ehlukanisayo isiza ekusabalaliseni ukukhanya ukuze igxile ngqo ku-retina.
Impendulo efanele ingu-B.
4. Ukwakheka kwesithombe esifanele kumaphutha e-myopic eye kungabonakala esithombeni...
Ingxoxo
I-Nearviewing noma i-myopia yisifo sokubona iso lapho iso lingakwazi ukubona izinto zikude ngokucacile.
Imbangela yokungaboni kahle yisimiso se-cornea-lens esigobile kakhulu (ingxenye evundlile yeso inde kakhulu) ukuze ubude bokugxila besistimu ye-cornea-lens buncishiswe, okubangela ukuthi imisebe yokukhanya evela endaweni ekude igxile phambi kwe-retina. Imisebe yokukhanya engenamkhawulo ayigxilile ku-retina ukuze amangqamuzana ezinzwa ku-retina angakwazi ukuguqula amaza okukhanya abe izimpawu zikagesi ezizodluliselwa ebuchosheni.
Impendulo efanele ngu-A.
5. Uma umuntu enenkinga yamehlo ecishe ibe ngu-50 cm, futhi efuna ukufunda ibanga elijwayelekile lokufunda (25 cm), umuntu kumele asebenzise izibuko ezinamandla ngelensi….
I-A. ½ dioptha
B. ¾ ama-diopter
C. 1 ½ diopters
D. 2 diopters
Ingxoxo
Umuntu ubona kude ngoba iphuzu eliseduze leso lakhe lingu-50 cm. Iphuzu eliseduze leso elivamile lingu-25 cm. Ukubona kude kulungiswa kusetshenziswa amalensi aqondile. Amalensi aqondile anobude obuhle bokugxila. Nakuba empeleni izibuko zisebangeni elithile ukusuka esweni, lokhu akunakwa kulesi sibalo.
Kuyaziwa ukuthi:
Umuntu onenkinga yeso eduze nendawo = ibanga lesithombe (s') = -50 cm
Isithombe kumele sibe phambi kwelensi eqondile ukuze sibonakale. Ngenxa yokuthi isithombe siphambi kwelensi eqondile, isithombe sibonakala nge-virtual futhi sinophawu olungalungile.
Ibanga lokufunda elijwayelekile = ibanga lezinto = 25 cm
Kubuziwe: Amandla amalensi engilazi
Impendulo:
Ubude be-focal yelensi eqondile (f):
1/f = 1/s + 1/s'
1/f = 1/25 – 1/50 = 2/50 – 1/50
1/f = 1/50
f = 50 cm
f = amamitha angu-0,5 = amamitha angu-5/10 = amamitha angu-1/2
Ubude be-focal lens ye-convex buhle ngoba imisebe yokukhanya idlula endaweni egxile kulens ye-convex.
Amandla ngelensi eqondile (P) yezibuko:
P = 1 /f = 1 : f
P = 1 : 1/2
P = 1 x 2/1
P = 2/1
P = ama-diopter ama-2
Amandla ngelensi eqondile yezibuko angama-diopters amabili.
Amandla ngelensi eqondile yezibuko ayakha ngoba ubude obuqondile belensi eqondile buyikhambi.
Impendulo efanele ngu-D.
6. Umuntu one-hyperopia angafunda incwadi ebangeni elingamasentimitha angu-125. Ukuze akwazi ukufunda ebangeni elijwayelekile elingamasentimitha angu-25, umuntu kumele agqoke izibuko ezinamandla ngelensi….
A. 3 1/5 diopters
B. 2 ½ diopters
C. 1 3/5 diopters
D. 1 ¼ diopters
Ingxoxo
Umuntu ubona kude ngoba iphuzu eliseduze leso lakhe lingu-125 cm. Iphuzu eliseduze leso elivamile lingu-25 cm. Ukubona kude kulungiswa kusetshenziswa amalensi aqondile.
Kuyaziwa ukuthi:
Umuntu onenkinga yeso eduze nendawo = ibanga lesithombe (s') = -125 cm
Isithombe kumele sibe phambi kwelensi eqondile ukuze sibonakale. Ngenxa yokuthi isithombe siphambi kwelensi eqondile, isithombe sibonakala nge-virtual futhi sinophawu olungalungile.
Ibanga lokufunda elijwayelekile = ibanga lezinto = 25 cm
Kubuziwe: Amandla amalensi engilazi
Impendulo:
Ubude be-focal yelensi eqondile (f):
1/f = 1/s + 1/s'
1/f = 1/25 – 1/125
1/f = 5/125 – 1/125
1/f = 4/125
f = 125/4
f = 31,25 cm
f = amamitha angu-0,3125
Amandla ngelensi eqondile (P) yezibuko:
P = 1/f
P = 1/0,3125
P = ama-diopter ama-3,2
P = (3)(2/10) ama-dioptha
P = (3)(1/5) ama-dioptha
Amandla ngelensi eqondile yezibuko angama-3,2 diopters = ama-3 1/5 diopters.
Impendulo efanele ngu-A.
7. Umuntu angafunda ngokucacile ebangeni elingamasentimitha angu-50. Ukuze akwazi ukufunda ngokucacile ebangeni elingamasentimitha angu-30, amandla amalensi ezibuko zamehlo adingekayo….
I-A. 1/3 dioptha
B. 2/3 diopters
C. ¾ diopters
D. 4/3 diopters
Ingxoxo
Kuyaziwa ukuthi:
Umuntu onenkinga yeso eduze nendawo = ibanga lesithombe (s') = -50 cm
Isithombe kumele sibe phambi kwelensi eqondile ukuze sibonakale. Ngenxa yokuthi isithombe siphambi kwelensi eqondile, isithombe sibonakala nge-virtual futhi sinophawu olungalungile.
Ibanga lokufunda = ibanga lezinto = 30 cm
Kubuziwe: Amandla amalensi engilazi
Impendulo:
Ubude be-focal yelensi eqondile (f):
1/f = 1/s + 1/s'
1/f = 1/30 – 1/50 = 5/150 – 3/150
1/f = 2/150
f = 150/2
f = 75 cm
f = amamitha angu-0,75 = amamitha angu-75/100 = amamitha angu-3/4
Amandla ngelensi eqondile (P) yezibuko:
P = 1 /f = 1 : f
P = 1 : 3/4
P = 1 x 4/3
P = 4/3 diopters
Amandla ngelensi eqondile yezibuko angama-4/3 diopters.
Impendulo efanele ngu-D.
8. Bheka isithombe esilandelayo sokwakheka kwesithunzi esweni!
Isici samehlo kanye namalensi engilazi asetshenziswa ukuqinisekisa ukuthi isithombe sise-retina….
Ingxoxo
Ukukhubazeka kwamehlo: ukubona eduze (i-myopia)
Ukukhanya kungagxila ngqo ku-retina uma kubekwe endaweni efanele ilensi egobile noma ilensi ehlukahlukene phambi kweso. Ilensi ehlukanisayo isiza ekusabalaliseni ukukhanya ukuze igxile ngqo ku-retina.
Impendulo efanele ngu-C.
Umthombo wombuzo:
Imibuzo Yokuhlolwa Kazwelonke Yesayensi Yesikole Samabanga Aphansi/Isikole SamaSulumane Samabanga Aphakeme
