Optics Question 16
Question: Assertion : The illumination of earth’s surface from sun is more at noon than in the morning. Reason : Luminance of a surface refers to brightness of the surface.
Options:
A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
C) If assertion is true but reason is false.
D) If the assertion and reason both are false.
E) If assertion is false but reason is true.
Show Answer
Answer:
Correct Answer: B
Solution:
At noon, rays of sun light fall normally on earth.
Therefore q = 0°. According to Lambert’s cosine law, $ E\propto \cos \theta , $ when q = 0°, cos q = cos 0° = 1 = max.
Therefore, E is maximum.
