Question

The intensity of direct sunlight on a surface normal to the rays is $I_{0}$. What is the intensity of direct sunlight on a surface, whose normal makes an angle of 60^o with the rays of the sun

• A. $I_{0}$
• B. $I_{0}\left( \frac{\sqrt{3}}{2} \right)$
• C. $\frac{I_{0}}{2}$
• D. $2I_{0}$

Answer 1

Answer: (C)

$\frac{I_{0}}{2}$

Answer 2

$I_{\theta} = I_{o}\cos\theta = I_{o}\cos 60^{o} = \frac{I_{o}}{2}$