Podcast
Questions and Answers
What happens to the intensity of rays from a source as the distance from that source increases?
What happens to the intensity of rays from a source as the distance from that source increases?
Which of the following laws describes the maximum absorption of energy when the source is at right angles to the absorbing surface?
Which of the following laws describes the maximum absorption of energy when the source is at right angles to the absorbing surface?
How do IR rays produce heat when absorbed?
How do IR rays produce heat when absorbed?
What is the effect of the angle of incidence on the proportion of rays absorbed according to the Cosine Law?
What is the effect of the angle of incidence on the proportion of rays absorbed according to the Cosine Law?
Signup and view all the answers
What is the characteristic of wireless waves when they are absorbed by tissues?
What is the characteristic of wireless waves when they are absorbed by tissues?
Signup and view all the answers
What is the relationship between wavelength and frequency in electromagnetic waves?
What is the relationship between wavelength and frequency in electromagnetic waves?
Signup and view all the answers
Which range of the electromagnetic spectrum is associated with ultraviolet (UV) radiation?
Which range of the electromagnetic spectrum is associated with ultraviolet (UV) radiation?
Signup and view all the answers
Which characteristic of electromagnetic waves influences their ability to penetrate tissues?
Which characteristic of electromagnetic waves influences their ability to penetrate tissues?
Signup and view all the answers
What occurs to the energy content of electromagnetic waves as the wavelength decreases?
What occurs to the energy content of electromagnetic waves as the wavelength decreases?
Signup and view all the answers
What is the primary use of microwaves in physical therapy?
What is the primary use of microwaves in physical therapy?
Signup and view all the answers
Which of the following electromagnetic waves is used primarily for tissue healing?
Which of the following electromagnetic waves is used primarily for tissue healing?
Signup and view all the answers
What occurs when infrared (IR), visible, and ultraviolet rays are absorbed by tissues?
What occurs when infrared (IR), visible, and ultraviolet rays are absorbed by tissues?
Signup and view all the answers
Which law governing radiation relates to energy transmission in tissues?
Which law governing radiation relates to energy transmission in tissues?
Signup and view all the answers
Study Notes
Electromagnetic Spectrum Overview
- All substances emit radiant energy as photons.
- Energy is transmitted through electromagnetic (e.m.) waves with a constant speed of 3 x 10^8 m/sec.
- Waves are defined by their wavelength (distance between corresponding points of consecutive waves) and frequency (number of cycles per unit time).
- The equation V = fλ combines velocity (V), frequency (f), and wavelength (λ).
Wave Properties
- Energy inversely correlates with wavelength; shorter wavelengths correspond to higher energy.
- Higher frequency results in greater energy content.
- Wave frequency influences the depth of penetration into tissues.
EM Spectrum Characteristics
- Ultraviolet (180-400 nm, 1.03 x 10^15 - 7.5 x 10^14 Hz) is used for diagnosis and therapy.
- Cold Laser (632 nm, 4.74 x 10^14 Hz) aids tissue healing.
- Infrared (800-15,000 nm, 2 x 10^14 - 2 x 10^13 Hz) is employed for superficial heat.
- Microwaves (1.5 x 10^4 - 3 x 10^8 Hz) and shortwaves (3 x 10^9 - 30 x 10^7 Hz) provide deep heat diathermy.
Effect of Heat and Chemical Reactions
- Infrared, visible, and ultraviolet rays are thermally produced; infrared heat promotes temperature increase in tissues (Grotthus’ Law).
- Ultraviolet rays induce chemical reactions, such as vitamin D formation.
- Wireless waves generate heat through high-frequency oscillating currents.
- Cold laser light does not generate heat upon absorption.
Wave Behavior Characteristics
- Waves exhibit reflection, refraction, absorption, and penetration.
- Reflection: Rays can be redirected based on wavelength, surface nature, striking angle, and reflector shape.
- Refraction: Occurs when waves bend upon entering a new medium.
- Absorption: Depends on the incident angle, described by the Cosine Law, where maximum absorption occurs at a right angle.
Laws Governing Radiation
- Law of Inverse Squares: Intensity diminishes inversely with the square of the distance from the source (ΔI = 1/(Δd)²).
- Bunsen Roscoe Law of Reciprocity: Intensity and duration of radiant energy doses are inversely related (E = It; E/t = I).
- Cosine Law: Maximum energy absorption occurs when the radiation source is perpendicular to the absorbing surface.
- Grotthus-Draper Law: The biological effect of rays is dependent on the energy absorbed.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz focuses on the electromagnetic spectrum and its relevance to physical therapy (PT). Students are expected to describe the spectrum, outline its sources and characteristics, and explain the pertinent laws governing radiation. Prepare to demonstrate your understanding of how these concepts apply in rehabilitation settings.
