Supiyanto Kelas X Evaluasi Bab 5 Nomor 6

Jika titik dekat mata seseorang 2 m, maka kuat lensa kacamata yang diperlukan adalah …

A. 0,25 D D. 2 D
B. 0,5 D E. 3,5 D
C. 1,5 D

Penyelesaian

Fokus lensa

\frac{1}{f}=\frac{1}{25}-\frac{1}{200}

\frac{1}{f}=\frac{7}{200}\frac{1}{\text{cm}}

 

Daya lensa

P=100\times \frac{7}{200}=3,5~\text{D}

Jawaban E

Supiyanto. 2006. FISIKA UNTUK SMA KELAS X. Jakarta: Phiβeta.

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