Final answer:
When a sonographer increases the amplitude of a wave by a factor of 3, the power of the wave is increased by a factor of 9.
Step-by-step explanation:
When a sonographer increases the amplitude of a wave by a factor of 3, the power of the wave also changes. In wave mechanics, the power of a wave is directly proportional to the square of the amplitude. Therefore, if the amplitude is increased by a factor of 3, the power is increased by a factor of 3 squared, which is 9.
The correct answer to how the power has changed when the amplitude of a wave has been increased by a factor of 3 is:
A. It has been increased by a factor of 9.