ARDMS Ultrasound Physics & Instrumentation Practice Exam

How is stiffness related to the hardness of a medium?

1. Directly proportional

2. Inversely proportional

3. Unrelated

4. Exponential relation

The correct answer is: Directly proportional

Stiffness is a measure of a material's resistance to deformation when a force is applied. In the context of ultrasound physics, the stiffness of a medium is directly related to its hardness. Harder materials demonstrate greater stiffness because they can better resist deformation under stress. This relationship implies that as the hardness of a medium increases, its stiffness also increases. In biomedical ultrasound, understanding this relationship is important because the stiffness of tissues influences the speed of sound waves as they travel through them. This is particularly relevant when measuring tissue characteristics in diagnostic imaging and assessing conditions such as tumors or liver stiffness. The direct proportionality suggests that both properties are interconnected, with an increase in one resulting in a corresponding increase in the other. This principle is fundamental in the study of acoustic properties of different materials used in ultrasound applications.