Consider the following information:
Waves are disturbances that propagate energy through a medium. Propagation of the energy depends on interactions between the particles that make up the medium. Particles move as the waves travel, but there is no net motion of particles. Thus, mechanical waves require matter through which to propagate. These waves are of the following types:
• Longitudinal waves: Movement of the particles is parallel to the direction the wave travels; that is, the direction of displacement is the same as the direction of propagation. Sound waves are longitudinal waves.
• Transverse waves: Movement of the particles is perpendicular to the direction the wave travels; that is, the direction of displacement is perpendicular to the direction of propagation. Movement of a wave through a stretched rope or a trampoline is an example of this type of wave.
Wavelength (λ) is the distance between identical points in the adjacent waves such as from crest to crest or trough to trough. It is measured in meters.
Frequency (f) describes the number of waves that passes a fixed place in a given amount of time. It is measured in hertz or cycles/s.
A period (T) is the time needed for one complete cycle of vibration to pass through a given point. Frequency (f) and period (T) have a reciprocal relationship that can be expressed mathematically as:
T = total time / number of cycles
→ T = 1 / frequency = 1 / f
The wave equation states the mathematical relationship between the speed (v) of a wave and its wavelength (λ) and frequency (f):
Speed = wavelength x frequency
→ v = λ x f
Or:
V = f / T since λ = 1 / f
The amplitude (A) of a wave refers to the maximum amount of displacement of a particle of the medium from its rest position
A swing completes a back-and-forth cycle every 2 seconds. What is the frequency of the swing?
Explanation
Frequency refers to the number of occurrences of a periodic event over time and is measured in cycles per second. In this case, there is one cycle per 2 seconds, so the frequency is 1 cycle/2 s = 0.5 Hz. Choice A is correct.
Employees at GetWell research labs are analyzing mechanical waves, which require a medium to pass through, and electromagnetic waves, which travel through space. Jose Gonzalez IV is studying electromagnetic waves and their potential, real-world health and medical applications. He records the lengths of the various waves, noting that radio waves are the longest, while Gamma rays are the shortest. When calculating the frequency of the wave, or the number of wavelengths that occur in a distinct amount of time, Jose notes that there is an inverse relationship between the frequency of a wave and its period, which is the time it takes for a single wave to occur.
Wave type | Wave length size | Application |
Radio Waves | Grater than 30cm | Aircraft Naviagtion, TV, AM/FM Radio |
Infrared Waves | 30cm - 1mm | Microwave Ovens, Mobile Phones |
Visible Light | 1mm - 700nm | Remote Controls, Toasters, Night Vision |
X-Rays | 700nm - 400nm | Physical Therapy, Light Bulbs, Photography |
Ultraviolet Light | 400nm - 60 nm | Sanitation, Air Purification, Forgery Detection |
X-Rays |
60nm - \(1 \times 10^{4}\)nm |
Medical Examination, Cancer Treatment |
Gamma Rays | 0.1 nm - \(1 \times 10^{5}\) nm | Cancer Treatment, Food Irradiation |
Based on the information provided, which types of waves have potential medical applications? Choose all that apply.