Question

Sun subtends an angle of $0.5^{\circ }$ at the centre of curvature of a concave mirror of radius of curvature $15m$ . 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
$=\frac{1}{2}\times \frac{\pi }{180}\times \frac{15}{2}\times 100cm=6.55cm$