Question

Sun subtends an angle of $0.5^{\circ} $ at the centre of curvature of a concave mirror of radius of curvature $15 \, m$ . The diameter of the image of the sun formed by the mirror is

• A. 8.55 cm
• B. 7.55 cm
• C. 6.55 cm
• D. 5.55 cm

Answer 1

Answer: (C)

$\theta=\frac{1}{2} \times \frac{\pi}{180} rad$
$\frac{\text { diametar of image }}{\text { focal length }}=\theta$
Or diameter of image
$=\frac{1}{2} \times \frac{\pi}{180} \times \frac{15}{2} \times 100\, cm =6.55 \,cm$