Question

Near and far points of human eye are

• A. 25 cm and infinite
• B. 50 cm and 100 cm
• C. 25 cm and 50 cm
• D. 0 cm and 25 cm

Answer 1

Answer: (A)

25 cm and infinite

Answer 2

The image formed in a microscope at least distance of distinct vision (D = 25 cm) has magnification $M = M_0 \times M_e$ where $M_0$ is magnification of objective lens and $M_e$ that of eyepiece. Also, $M = M_0 \bigg(1+ \frac{D}{f_e}\bigg)$ Given, $f_e = 5 cm, D = 25\, cm$ and $M = 30$ $30 = M_0 \times \bigg(1+ \frac{25}{5}\bigg)$ $M_0 = \frac{30}{6} = 5$