If amplitude is doubled, what happens to intensity?

When amplitude is doubled, the intensity of the ultrasound wave increases by a factor of four, which is why the correct answer is that it quadruples. This relationship arises from the physics of wave propagation.

Intensity is defined as the power per unit area, and it is directly proportional to the square of the amplitude of the wave. This means that if the amplitude (the height of the wave) is increased, the intensity (which relates to how much energy the wave carries) increases according to the square of that change.

For instance, if the initial amplitude is represented as 'A,' and it is doubled to '2A,' the new intensity can be calculated as follows:

1. Original intensity = A²

2. New amplitude = 2A

3. New intensity = (2A)² = 4A²

Thus, the intensity quadruples when the amplitude is doubled. This principle is crucial in sonography, as it helps in understanding how changes in wave properties affect the resulting imaging characteristics, including the brightness and the quality of the ultrasound images produced.