Podcast
Questions and Answers
What is a characteristic of electromagnetic radiation (EMR)?
What is a characteristic of electromagnetic radiation (EMR)?
- EMR can travel faster than the speed of light.
- EMR has no defined frequency or wavelength.
- EMR always travels in straight lines. (correct)
- EMR requires a medium to travel.
Which statement correctly describes ionizing EMR?
Which statement correctly describes ionizing EMR?
- Ionizing EMR cannot penetrate human tissue.
- Ionizing EMR is primarily used for therapeutic applications only.
- Ionizing EMR can easily break molecular bonds. (correct)
- Ionizing EMR includes low-frequency radiation.
Which relationship is accurate regarding wavelength and frequency of EMR?
Which relationship is accurate regarding wavelength and frequency of EMR?
- Increasing wavelength decreases frequency.
- Wavelength is directly proportional to frequency.
- Wavelength is inversely proportional to frequency. (correct)
- Wavelength and frequency are independent of each other.
What happens to electrons when a material is induced with electromagnetic radiation?
What happens to electrons when a material is induced with electromagnetic radiation?
Which of the following is an example of non-ionizing EMR?
Which of the following is an example of non-ionizing EMR?
Which property distinguishes the speed of EMR in a vacuum?
Which property distinguishes the speed of EMR in a vacuum?
What phenomenon occurs when an electromagnetic wave bounces back from an object?
What phenomenon occurs when an electromagnetic wave bounces back from an object?
What type of electromagnetic radiation is typically used for diagnostic purposes in medicine?
What type of electromagnetic radiation is typically used for diagnostic purposes in medicine?
What principle dictates that the angle of incidence is equal to the angle of reflection?
What principle dictates that the angle of incidence is equal to the angle of reflection?
Which factor does NOT influence the degree of absorption and penetration of EMR through a medium?
Which factor does NOT influence the degree of absorption and penetration of EMR through a medium?
What law explains that a certain intensity of EMR is needed to initiate a biological process?
What law explains that a certain intensity of EMR is needed to initiate a biological process?
What is true about EMR that falls at a 90-degree angle to a medium?
What is true about EMR that falls at a 90-degree angle to a medium?
Which law states that the energy received by tissue decreases as the distance from the source increases?
Which law states that the energy received by tissue decreases as the distance from the source increases?
What is the relationship between wavelength and scattering in non-homogenous media?
What is the relationship between wavelength and scattering in non-homogenous media?
Which of the following is NOT a contraindication for EMR therapy?
Which of the following is NOT a contraindication for EMR therapy?
What happens to EMR energy that is not absorbed in superficial tissues, according to the Grotthus-Draper Law?
What happens to EMR energy that is not absorbed in superficial tissues, according to the Grotthus-Draper Law?
Flashcards
Electromagnetic radiation (EMR)
Electromagnetic radiation (EMR)
Energy traveling as electric and magnetic fields perpendicular to each other and the direction of radiation. It covers a wide range of wavelengths and frequencies.
Electromagnetic spectrum
Electromagnetic spectrum
The range of EMR frequencies and wavelengths.
Speed of light
Speed of light
The constant speed at which all EMR travels in a vacuum (300,000,000 m/s).
Wavelength
Wavelength
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Frequency (EMR)
Frequency (EMR)
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Ionizing EMR
Ionizing EMR
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Non-ionizing EMR
Non-ionizing EMR
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Photon
Photon
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Angle of incidence = Angle of reflection
Angle of incidence = Angle of reflection
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Factors affecting reflection
Factors affecting reflection
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Refraction
Refraction
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Factors affecting refraction
Factors affecting refraction
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Absorption and penetration
Absorption and penetration
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Factors affecting absorption and penetration
Factors affecting absorption and penetration
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Inverse square law
Inverse square law
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Cosine law
Cosine law
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Study Notes
Radiation
- Energy that travels and spreads out
- Electromagnetic radiation (EMR)
Electromagnetic Radiation (EMR)
- Composed of electric and magnetic fields perpendicular to each other and the direction of radiation
- Covers a broad spectrum of wavelengths and frequencies
Electromagnetic Spectrum
- EMR arranged by frequency and wavelength
Electromagnetic Wave Production
- Steps
- Applying a strong electrical or chemical force to a material
- Causing electrons to move to higher energy levels (excited state)
- Electrons return to their original energy level
- Energy released as a pulse of EMR (photon)
- Energy released depending on wavelength or frequency difference
EMR Characteristics
- Travels at a constant speed (speed of light) in a vacuum (300 million m/s)
- Does not require a medium to travel
- Can be reflected, absorbed, or refracted depending on the medium
Wavelength and Frequency
- Wavelength: Distance between two wave peaks
- Frequency: Number of waves passing a point per second (Hertz)
- Speed of light = wavelength x frequency
- Frequency is directly related to radiating energy and inversely to wavelength
Ionizing vs. Non-ionizing EMR
- Ionizing: High-frequency radiation (X-rays, gamma rays)
- High energy capable of breaking molecular bonds
- Can cause cell damage and mutations
- Used in medical diagnoses and treatments (in small doses)
- Non-ionizing: Low-frequency radiation (radio waves, microwaves, infrared, visible light, ultraviolet)
- Low energy, does not break molecular bonds
- Generally safe for use in therapeutic applications
Physical Laws Governing EMR Effects
- Reflection: EMR bouncing off an object
- Angle of incidence = angle of reflection
- Refraction: EMR changing direction when passing from one medium to another.
- Absorption & Penetration: EMR being absorbed or passing through a medium. Penetration and absorption vary based on wavelength, frequency, nature of medium, and intensity.
- Scattering: EMR changing direction when passing through a non-homogeneous medium (related to wavelength)
- Inverse Square Law: EMR's intensity decreases with the square of the distance from the source
Other Important Laws
- Cosine Law: Effective energy of radiation is dependent on the angle of incidence
- Arndt-Schulz Law: A minimum intensity of EMR is required to cause a physiological change in tissue
- Grotthus-Draper Law: If energy is not absorbed in surface tissue, it will penetrate to deeper tissues. Energy absorption in tissue is impacted by frequency.
Examples of EMR Modalities
- Shortwave diathermy
- Light therapy
- Infrared radiation
- Ultraviolet radiation ("phototherapy")
- Low-power lasers
Contraindications of EMR
- Pregnancy
- Pacemakers
- Recent deep X-ray therapy
- Metastasis or malignancy
- Metal implants
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Description
Explore the key concepts of electromagnetic radiation including its production, characteristics, and the electromagnetic spectrum. This quiz covers essential principles such as the behavior of EMR, wavelength, and frequency. Test your understanding of how energy propagates through different mediums.
