Question

Why is the light falling on a slanted surface less bright?

Answer 1

Answer:

Light that falls on a slanted surface is weaker and less bright because it covers and spreads over a larger area and gets diffused. On the other hand, light that falls on a straight surface actually covers a smaller area and hence becomes concentrated and brighter.

The same theory is followed in case of the light of the Sun reaching the Earth's surface in different latitudes and hence the intensity varies accordingly.