Question

The diameter of the pupil of human eye is about $2 \,mm$. Human eye is most sensitive to the wavelength of $555\, nm$. The limit of resolution of human eye is

• A. $1.2$ min
• B. $2.4$ min
• C. $0.6$ min
• D. $0.3$ min

Answer 1

Answer: (A)

$1.2$ min

Answer 2

Limit of resolution, $d\theta = \frac{1.22 \lambda}{D}$ $=\frac{ 1.22 \times 555 \times 10^{-9}}{2 \times 10^{-3}}$ $= 3.39 \times 10^{-4} rad$ $d\theta = 3.39 \times 10^{-4} \times \left(\frac{180^{\circ}}{\pi}\right)$ $= 0.0194^{\circ}$ $= 0.0194 \times 60'$ $= 1.2'$