Different types of waves are used in science, communication, and medicine.
Some waves are electromagnetic.
Which of these properties is the same for all electromagnetic waves travelling through a vacuum?
Match each type of electromagnetic wave with its correct use.
Light waves are transverse waves. Describe how the vibrations (oscillations) of a transverse wave relate to the direction in which the wave travels.
Ultrasound waves can be used in medical diagnostics, such as obstetric sonography to monitor fetal development.
The frequency of ultrasound is higher than the upper limit of human hearing. Which of these could be the frequency of a diagnostic medical ultrasound wave?
A medical scanner measures the time delay between sending an ultrasound pulse into the body and receiving the reflected echo from the surface of an internal organ. The distance to the organ is calculated using:
distance=speed of sound in tissue×time recorded2 \text{distance} = \frac{\text{speed of sound in tissue} \times \text{time recorded}}{2} distance=2speed of sound in tissue×time recordedExplain why the division by 2 is used in this equation.
The speed of sound in muscle tissue is faster than the speed of sound in fat tissue. Explain how this increase in speed affects the wavelength of the ultrasound wave when it passes from fat tissue into muscle tissue, assuming its frequency does not change.
