Chapter 3: Electromagnetic Radiation and Radiation Concepts

A comprehensive set of Q&A flashcards covering electromagnetic radiation principles, spectrum, interactions with matter, particulate radiation, radioactivity, exposure, and radiography concepts from the lecture notes.

What is electromagnetic radiation?

An electric and magnetic disturbance traveling through space at the speed of light.

Do all electromagnetic radiations have the same velocity?

Yes—the speed of light (about 3 × 10^8 m/s) for all EM radiation.

What are the main properties that vary among different electromagnetic radiations?

Energy, wavelength, and frequency.

How is the electromagnetic spectrum organized?

As a grouping of different radiations by energy, wavelength, and frequency, all traveling at the same speed.

Can electromagnetic radiation exist without matter?

Yes; it is energy that can travel through a vacuum and originate from atoms.

What does 'divergent rays' mean in EM radiation and what describes intensity?

EM radiation diverges from its source; intensity is the energy flow per second (photon count), with the greatest intensity typically at the center.

How else can electromagnetic radiation be characterized besides energy, wavelength, and frequency?

By how it interacts with matter; its intensity diminishes with distance.

What does the inverse square law state about radiation intensity?

Intensity falls off with distance roughly as I ∝ 1/d^2.

List the components of the electromagnetic spectrum from lowest energy to highest.

Radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays.

What are the typical wavelength and frequency ranges for EM radiation?

Wavelengths range about 10^6 to 10^-16 meters; frequencies range about 10^2 to 10^24 Hz.

What is wave-particle duality?

Electromagnetic radiation can exhibit both wave-like and particle-like properties depending on energy and environment.

What is the relationship between wavelength and frequency for EM radiation?

They are inversely related; v = fλ; for EM radiation, velocity is the speed of light, c.

What is the simplified velocity formula used for electromagnetic radiation?

c = fλ; equivalently f = c/λ; λ = c/f; and v = fλ.

How is energy related to frequency for EM radiation?

Energy is proportional to frequency: E = hf.

What is Planck’s constant as given in the notes?

h = 4.15 × 10^-15 eV·s.

What is the stated energy range of electromagnetic radiation?

From about 10^-12 to 10^10 electron volts (eV).

Is the range of electromagnetic energy continuous?

Yes; the energy, frequency, and wavelength span a continuous range.

What are the rest spectrum uses and ionization properties of radio waves?

Radio waves are used in MRI and do not ionize atoms.

Do microwaves ionize atoms?

No; they are used for cell signals and heating and do not ionize.

Do infrared and visible light ionize atoms?

No; infrared is used for information transmission, and visible light does not ionize.

Does ultraviolet light ionize atoms?

According to the notes, it does not ionize atoms, though it has energies approaching x-rays and gamma rays and can be harmful.

Which radiations ionize matter?

X-rays and gamma rays ionize matter.

Where do gamma rays originate from?

From the nuclei of atoms as excess energy released to reach a stable state.

Where do X-rays originate from?

Through interactions between electrons and atoms.

What is particulate radiation and what are its main types?

Radiation composed of particles, mainly alpha and beta particles, which can ionize matter.

Describe alpha particles.

Two protons and two neutrons bound together; positive charge; short range; cannot penetrate most objects.

Describe beta particles.

Electrons emitted from unstable nuclei; lighter than alpha; may ionize along their path; originate from the nucleus, not the electron shell.

What charges can beta particles have?

Both negative (electron) and positive (positron) beta particles can occur.

What happens when beta particles collide with atoms?

They join with atoms just as electrons do, potentially causing ionization.

What is radioactivity?

The process by which an atom with excess nuclear energy emits particles and energy to regain stability.

What is a half-life?

The time required for half of the remaining atoms in a sample to decay.

What are the sources of radiation exposure?

Natural/background (cosmic, terrestrial, internal) and manmade (medical); total dose varies by geographic location.

What are the four main interactions of energy with matter in practice?

Reflection, transmission, absorption, and attenuation.

What is the difference between radiopaque and radiolucent materials?

Radiopaque materials (like bone) appear white; radiolucent materials (like soft tissue) appear darker on X-ray images.

What is a radiographer’s role in relation to radiation safety and patient care?

Be familiar with different radiation types, educate patients, understand the spectrum, explain ionizing radiation, advocate for the patient, and use radiation safely.