Question

ﹰCalculate the power of a lens of focal lenght 20 cm​

Answer 1

Answer:

so, 20 CM in metres= 20/100m=1/5 metres. power of a lens= 1/1/1/5=5 dioptres

Step-by-step explanation:

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Answer 2

Answer:

Power= +5 D (dioptre)

Step-by-step explanation:

Power=P = 1/f in metres

               = 100/f in centimetres

       Since f= 20cm

     P= 100/20 = 5

         Therefore Power = 5 dioptre or +5 D

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