Question

9 multiple choice 2 points
an echo heard when a person shouts in a canyon is due to the sound waves being
mixed
refracted
diffracted
reflected
10 multiple choice 2 points
which wave phenomenon makes it possible for a player to hear the sound from a
referees whistle in an open field even when standing behind the referee?
diffraction
doppler effect
reflection
refraction
11 multiple choice 2 points
which waves require a medium for transmission?
light waves
radio waves
sound waves
cosmic waves

Explanation:

• Question 9: Echo is due to sound waves bouncing back (reflection).
• Question 10: Diffraction allows waves to bend around obstacles (like the referee), enabling sound to reach the player behind.
• Question 11: Sound waves need a medium (solid, liquid, gas) for transmission. Light, radio, and cosmic waves can travel in a vacuum.

Answer:

• Question 9: D. reflected
• Question 10: A. diffraction
• Question 11: C. sound waves