Waves are used in many practical applications to support work, entertainment, and health. One example is the use of ultrasound imaging to safely track the development of a growing fetus. What is a specific example of a practical application of waves in medicine, entertainment, safety, or other fields? Provide a brief explanation of how the properties of waves are useful to that application.

Waves are useful to send signals from one point in space to another point in space. For example, the control remote of the tv works with electromagnetic waves, each time you push a button, the remote control sends a signal, as an electromagnetic wave, that is detected and interpreted by the tv.

The property here is that waves can deliver information.

Medicine: Radiation is used as a treatment for some type of tumors, this is because some types of radiation can cause cellular death, so if you irradiate a tumor for long enough, you can "kill it". Radiation is also useful to do things like radiography, where the electromagnetic waves interact with the dense materials in our body, the bones, and allow us to see the state of our bones in a non-intrusive way.

So the properties used here are that waves can deliver a lot of energy, and can interact in different ways with different materials.

Safety: Electromagnetic waves may be used in security systems, as the example for the control remote, you can use a device that is constantly sending a signal (an electromagnetic wave), and when the electromagnetic wave rebounds in the wall it returns to the device, and the device reads the wave (it actually reads the difference in the time between the moment when the wave is sended and when the wave is detected again).

If some object (like a person) stands between the device and the wall, the electromagnetic wave will rebound in the person and will be detected by the device, and as the person is closer to the device than the wall, the device will detect that the rebounded wave arrived earlier, at this moment the alarm is triggered.

Here we use that a wave always move at the same velocity (this is why the one that rebounds earlier reaches the device earlier) and that electromagnetic waves can rebound in most surfaces.