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Question Number 41964 by Necxx last updated on 16/Aug/18

Prof Kintush has a near point of  45cm and his far point is infinity.  What type of lens and focal length  should be recommended for his  normal reading?

$${Prof}\:{Kintush}\:{has}\:{a}\:{near}\:{point}\:{of} \\ $$$$\mathrm{45}{cm}\:{and}\:{his}\:{far}\:{point}\:{is}\:{infinity}. \\ $$$${What}\:{type}\:{of}\:{lens}\:{and}\:{focal}\:{length} \\ $$$${should}\:{be}\:{recommended}\:{for}\:{his} \\ $$$${normal}\:{reading}? \\ $$

Commented by tanmay.chaudhury50@gmail.com last updated on 16/Aug/18

Commented by tanmay.chaudhury50@gmail.com last updated on 16/Aug/18

Commented by tanmay.chaudhury50@gmail.com last updated on 16/Aug/18

Commented by tanmay.chaudhury50@gmail.com last updated on 16/Aug/18

Commented by tanmay.chaudhury50@gmail.com last updated on 16/Aug/18

Commented by tanmay.chaudhury50@gmail.com last updated on 16/Aug/18

Commented by tanmay.chaudhury50@gmail.com last updated on 16/Aug/18

Commented by tanmay.chaudhury50@gmail.com last updated on 16/Aug/18

Commented by tanmay.chaudhury50@gmail.com last updated on 16/Aug/18

Commented by tanmay.chaudhury50@gmail.com last updated on 16/Aug/18

Answered by tanmay.chaudhury50@gmail.com last updated on 16/Aug/18

taking reference from the attached comments  this is hyperopic ...  lense should be converging  that means   bi convex lense...  d_0 =25cm   d_1 =−45cm  f=((d_0 ×d_1 )/(d_0 +d_1 ))=((25×−45)/(−25))=+56.25cm  p=(1/(f(in meter)))=(1/(0.5625))=1.78  pls check...

$${taking}\:{reference}\:{from}\:{the}\:{attached}\:{comments} \\ $$$${this}\:{is}\:{hyperopic}\:... \\ $$$${lense}\:{should}\:{be}\:{converging}\:\:{that}\:{means}\: \\ $$$${bi}\:{convex}\:{lense}... \\ $$$${d}_{\mathrm{0}} =\mathrm{25}{cm}\:\:\:{d}_{\mathrm{1}} =−\mathrm{45}{cm} \\ $$$${f}=\frac{{d}_{\mathrm{0}} ×{d}_{\mathrm{1}} }{{d}_{\mathrm{0}} +{d}_{\mathrm{1}} }=\frac{\mathrm{25}×−\mathrm{45}}{−\mathrm{25}}=+\mathrm{56}.\mathrm{25}{cm} \\ $$$${p}=\frac{\mathrm{1}}{{f}\left({in}\:{meter}\right)}=\frac{\mathrm{1}}{\mathrm{0}.\mathrm{5625}}=\mathrm{1}.\mathrm{78} \\ $$$${pls}\:{check}... \\ $$

Commented by Necxx last updated on 17/Aug/18

wow...Thank you so much sir Tanmay  please what pdf is this I′ll like to  download it . It seems more explanatory  than the others I have.

$${wow}...{Thank}\:{you}\:{so}\:{much}\:{sir}\:{Tanmay} \\ $$$${please}\:{what}\:{pdf}\:{is}\:{this}\:{I}'{ll}\:{like}\:{to} \\ $$$${download}\:{it}\:.\:{It}\:{seems}\:{more}\:{explanatory} \\ $$$${than}\:{the}\:{others}\:{I}\:{have}. \\ $$

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