Izibonelo ezimbili zemibuzo ye-convex convex double lens
1. Amalensi amabili aqondile, ngalinye linobude obungamasentimitha angama-20 no-30, abekwe eduze, ibanga eliphakathi kwamalensi amabili aqondile lingu-70 cm. Into ingamasentimitha angama-30 phambi kwelensi yokuqala. Thola ibanga lesithombe kanye nokukhulisa isithombe esakhiwe amalensi amabili. ilensi eqondile thula!
Ingxoxo
Kuyaziwa ukuthi:
Ubude obuqondile belensi yokuqala eqondile (f)1) = +20 cm
Ubude bokugxila belensi yesibili eqondile (f)2) = +30 cm
Ubude be-focal lens eqondile buyinto enhle ngoba ukukhanya kudlula endaweni eqondile yelens eqondile.
Ibanga phakathi kwamalensi amabili aqondile (l) = 50 cm
Ibanga lento kusukela kulensi yokuqala eqondile (s)1= 30cm
Ibanga lento lihle ngoba ukukhanya kuvela entweni.
Impendulo:
a) Ibanga lesithunzi
Ibanga lesithombe elakhiwe ilensi yokuqala eqondile (ibanga lesithombe sokuqala):
I-1 / s1' = 1/f1 – 1/s1
I-1 / s1' = 1/20 – 1/30 = 3/60 – 2/60 = 1/60
s1' = 60/1 = 60 cm
Isithombe sokuqala singama-60 cm ukusuka kulensi eqondile 1.
Ibanga lesithombe sokuqala lihle, okusho ukuthi isithombe sokuqala singokoqobo, okusho ukuthi sikhona ngempela ngoba ukukhanya kudlula esithombeni.
Ibanga lesithombe elakhiwe ilensi yesibili eqondile (ibanga lokugcina lesithombe):
Isithombe esakhiwe yilensi yokuqala eqondile sibhekwa njengento yilensi yesibili eqondile. Ibanga lesithombe/into yokuqala kusukela kulensi yesibili eqondile (s)2) = ibanga phakathi kwamalensi amabili aqondile – ibanga lesithombe sokuqala kusukela kulensi yokuqala eqondile = 70 cm – 60 cm = 10 cm.
I-1 / s2' = 1/f2 – 1/s2
I-1 / s2'= 1/30 – 1/10 = 1/30 – 3/30 = -2/30
s2' = -30/2 = -15 cm
Isithombe sokugcina singama-15 cm ukusuka kulensi yesibili eqondile.
Ibanga lesithombe sokugcina liyi-negative, okusho ukuthi isithombe sokugcina singesilo iqiniso noma singamanga ngoba isithombe asidluliswanga yi-light beam (isithombe sokugcina sikwesobunxele selensi yesibili eqondile).
b) Ukukhulisa isithombe
Ukukhulisa isithombe ngelensi yokuqala eqondile:
m1 = -s1'/s1 = -60 cm/30 cm = -2 izikhathi
Ilensi eqondile ibangela ukuthi usayizi wesithombe ube mkhulu ngokuphindwe kathathu kunosayizi wento.
Ukukhulisa isithombe ngophawu olunegethivu kusho ukuthi isithombe siphendukezelwe.
Ukukhulisa isithombe ngelensi yesibili eqondile:
m2 = -s2'/s2 = -(-15 cm)/10 cm = 15/10 = izikhathi ezingu-1,5
Ilensi yesibili eqondile ikhulisa into (isithombe selensi yokuqala eqondile) ngesilinganiso esingu-1,5.
Ukwandiswa okuphelele kwesithombe yilokhu:
m = (m1)(m2) = (-2)(1,5) = -3 izikhathi
Usayizi wesithombe sokugcina mkhulu ngokuphindwe kathathu kunosayizi wento noma ukuphakama kwesithombe sokugcina kuphakeme ngokuphindwe kathathu kunokuphakama kwento. Ukukhulisa okuphelele kuphambene okusho ukuthi isithombe siguquliwe. (isithombe sokugcina siguquliwe ngakho isithombe sokugcina kumele sibe ngakwesobunxele selensi yesibili eqondile).
2. Ibanga eliphakathi kwamalensi amabili acwebezelayo lingu-100 cm. Amalensi amabili acwebezelayo ngalinye linobude obuqondile obungu-20 cm no-80 cm. Into ingama-30 cm phambi kwelensi yokuqala. Thola ibanga lesithombe kanye nokukhulisa isithombe esakhiwe amalensi amabili acwebezelayo!
Ingxoxo
I-Diketahui :
Ibanga phakathi kwamalensi amabili (l) = 100 cm
Ubude obuqondile belensi yokuqala eqondile (f)1= 20cm
Ubude bokugxila belensi yesibili eqondile (f)2= 80cm
Ubude be-focal lens eqondile buyinto enhle ngoba ukukhanya kudlula endaweni eqondile yelens eqondile.
Ibanga lento kusukela kulensi yokuqala eqondile (s)1= 30cm
Ibanga lento lihle ngoba ukukhanya kuvela entweni.
Jawab :
a) Ibanga lesithunzi
Ibanga lesithombe elakhiwe ilensi yokuqala eqondile (ibanga lesithombe sokuqala):
I-1 / s1' = 1/f1 – 1/s1
I-1 / s1' = 1/20 – 1/30 = 3/60 – 2/60 = 1/60
s1' = 60/1 = 60 cm
Isithombe sokuqala singama-60 cm ukusuka kulensi eqondile 1.
Ibanga lesithombe sokuqala lihle, okusho ukuthi isithombe sokuqala singokoqobo, okusho ukuthi sikhona ngempela ngoba ukukhanya kudlula esithombeni.
Ibanga lesithombe elakhiwe ilensi yesibili eqondile (ibanga lokugcina lesithombe):
Isithombe esakhiwe yilensi yokuqala eqondile sibhekwa njengento yilensi yesibili eqondile. Ibanga lesithombe/into yokuqala kusukela kulensi yesibili eqondile (s)2) = ibanga phakathi kwamalensi amabili aqondile – ibanga lesithombe sokuqala kusukela kulensi yokuqala eqondile = 100 cm – 60 cm = 40 cm.
I-1 / s2' = 1/f2 – 1/s2
I-1 / s2'= 1/80 – 1/40 = 1/80 – 2/80 = -1/80
s2' = -80/1 = -80 cm
Isithombe sokugcina singama-80 cm ukusuka kulensi yesibili eqondile.
Ibanga lesithombe sokugcina liyi-negative, okusho ukuthi isithombe sokugcina singesilo iqiniso noma singamanga ngoba isithombe asidluliswanga yi-light beam (isithombe sokugcina sikwesobunxele selensi yesibili eqondile).
b) Ukukhulisa isithombe
Ukukhulisa isithombe ngelensi yokuqala eqondile:
m1 = -s1'/s1 = -60 cm/30 cm = -2 izikhathi
Ilensi eqondile ibangela ukuthi usayizi wesithombe ube mkhulu ngokuphindwe kathathu kunosayizi wento.
Ukukhulisa isithombe ngophawu olunegethivu kusho ukuthi isithombe siphendukezelwe.
Ukukhulisa isithombe ngelensi yesibili eqondile:
m2 = -s2'/s2 = -(-80 cm)/40 cm = 80/40 = izikhathi ezingu-2
Ilensi yesibili eqondile ikhulisa into (isithombe selensi yokuqala eqondile) ngesilinganiso esingu-2.
Ukwandiswa okuphelele kwesithombe yilokhu:
m = (m1)(m2) = (-2)(2) = -4 izikhathi
Usayizi wesithombe sokugcina mkhulu ngokuphindwe kane kunosayizi wento noma ukuphakama kwesithombe sokugcina kuphakeme ngokuphindwe kane kunokuphakama kwento. Ukukhulisa okuphelele kuphambene okusho ukuthi isithombe siguquliwe (isithombe sokugcina siguquliwe ngakho isithombe sokugcina kumele sibe ngakwesobunxele selensi yesibili eqondile).
Imibuzo yelensi ephindwe kabili egobile egobile
1. Amalensi amabili aqondile ngalinye elinobude obungamasentimitha angu-40 no-20 abekwe eduze lapho ibanga eliphakathi kwamalensi amabili aqondile lingu-100 cm. Thola ibanga lesithombe kanye nokukhulisa okuphelele kwesithombe esakhiwe amalensi amabili aqondile entweni engamasentimitha angu-120 phambi kwelensi yokuqala eqondile!
Ukhiye wempendulo:
(a) ibanga lokugcina lesithombe = s2' = 40
(b) ukukhuliswa okuphelele kwesithombe = m = 0,5
2. Into ingamamitha ayi-10 ngakwesobunxele ngelensi eqondile enobude obuqondile obungamasentimitha angama-20. Ngakwesokudla ngelensi eqondile kukhona ilensi eqondile enobude obuqondile obungamasentimitha angama-50. Uma ibanga eliphakathi kwamalensi amabili lingu-120 cm, nquma ibanga lesithombe kanye nokukhulisa isithombe esakhiwe amalensi amabili aqondile!
Ukhiye wempendulo:
(a) ibanga lokugcina lesithombe = s2' = 133 cm
(b) ukukhuliswa okuphelele kwesithombe = m = -1,7 izikhathi. Okubi kusho ukuthi isithombe siphendukezelwe.
