Question

A group of students are doing a reading activity in their classroom. They suddenly hear the noise of a truck in the parking lot of their school. They can hear it but cannot see it. Which of the following explains why they can hear the truck, but cannot see it?
A.
Sound can be transmitted through all materials through which visible light cannot.
B.
Sound can be transmitted faster than visible light.
C.
Sound can be transmitted slower than visible light.
D.
Sound can be transmitted through the walls, but visible light cannot.

Answer 1

D.

Sound is a mechanical wave that can travel through solids (and diffract/reflect around obstacles and through openings), so the noise can reach the classroom even when the truck is out of the line of sight. Visible light requires a clear line of sight and is blocked by walls, so they cannot see the truck.