DMI 105 Module 3

Speed of Light

(c ) 3.0 x 108 m/s)

Electromagnetic radiation

(energy) an electric and magnetic disturbance traveling through space at the speed of light.

The half-life of technetium 99m is eight hours. If you have 12mCi of technetium at this moment, how much will remain in 24 hours? 6.0 mCi , 3.0 mCi , 1.5 mCi, or 0.75 mCi

1.5 mCi B7 In this scenario, the technetium will go through three half-lives in 24 hours (24/8). So we divide the original dose in half three times (12 to 6, 6 to 3, 3 to 1.5).

Which frequency is outside the electromagnetic spectrum:

10-2 ; The frequency of the electromagnetic spectrum is from 102 to 1024m; therefore, 10-2 is outside of this range.

Which frequency will have the longest wavelength? 102, 104, 106 or 108 Hz.

102: The lower the frequency, the longer the wavelength.

How many neutrons does an alpha particle have?

2 Alpha particles have two protons and two neutrons but no electrons.

What is the wavelength of electromagnetic radiation with a frequency of 1 x 1010 Hz?

3 x 10-2 m To find wavelength, we divide the c (the speed of light) by the frequency: 3 x 108m/s divided by 1 x 1010 Hz.

Electron volts

A measure of the energy of a moving electron or x-ray photon; abbreviated as eV. An electron has 1 eV when it is accelerated by an electric potential of 1 volt (V).

Curie

A measure of the rate of radioactive decay; the amount of material that has 37 billion nuclei decaying in 1 second; abbreviated as Ci.

Photons

A packet of energy that has no mass; all electromagnetic energy, including light and x-rays, is in the form of photons.

Alpha particle

A particle that has two protons bound to two neutrons, but no electrons. This particle has the same nucleus as a helium atom, but an alpha particle is not an atom because it has no electrons.

Radionuclide

A radioactive atom

Becquerel

A unit of radioactivity, defined as that of quantity of a radioactive nuclide whose rate of spontaneous nuclear transformation is one decay event per second (1 s-1); 1 curie equals 3.7 x 1010 becquerels; 1 microcurie equals 37 kilobecquerels.

What distinguishes x-rays and gamma rays apart from the rest of the electromagnetic spectrum?

Ability to ionize matter: The unique characteristic of x-rays and gamma rays as members of the electromagnetic spectrum is their ability to remove electrons from atoms (ionize matter).

Which of the following has a positive charge? Alpha, Beta, Gamma

Alpha : Alpha particles have a positive charge; beta particles have a negative charge.

Which wave characteristic refers to the height of a wave?

Amplitude Amplitude is the height of a wave. Speed is the velocity at which it travels

Beta particle

An electron that forms inside an unstable nucleus and is immediately ejected as a type of radioactive decay.

A beta particle is an electron that originates from?

An unstable nucleus Although beta particles are electrons that have a negative charge, they originate from an unstable nucleus.

Which of the following is not a member of the electromagnetic spectrum?

Beta The members of the spectrum are radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma rays. Beta is a particle and not a part of the electromagnetic spectrum.

If wavelength increases, what happens to frequency?

Decreases Wavelength is the distance between sequential peaks, and frequency is the number of waves per second.

In what medium does electromagnetic radiation travel best?

Does not require a medium With electromagnetic radiation, it is the energy itself that vibrates and it does not require a medium in which to travel.

Electromagnetic radiation includes what types of disturbances in space?

Electric & Magnetic By definition, electromagnetic radiation is an electric and magnetic disturbance traveling through space at the speed of light.

What does wave-particle duality mean?

Electromagnetic radiation has characteristics of waves and particles. Wave-particle duality means that electromagnetic radiation has characteristics of both waves and particles and, depending on the circumstance, will exhibit both.

What differentiates x-rays from gamma rays?

Energy, source, Frequency: Gamma rays are at the top end of the spectrum, just above x-rays, making their energy and frequency greater. Gamma rays also originate from unstable nuclei; whereas, x-rays originate from electrons interacting with atoms.

Planck's Quantum Theory describes a relationship between what two things?

Frequency and Energy; Physicist Max Planck first described the relationship between frequency and energy.

Which of the following has the highest energy?

Gamma rays X-rays and gamma rays are at the high end of the electromagnetic spectrum, but it is gamma rays that are at the top of the list.

Gamma rays

Gamma rays are electromagnetic radiation like x-rays and light rays, but they originate in the nuclei of atoms.

Radioactivity

General term for the processes by which atoms with unstable nuclei radiate excess energy in the form of particles and energy.

Which end (high or low) of the electromagnetic spectrum is more likely to exhibit characteristics of particles?

High end

What happens to photon energy as frequency increases?

Increase; Photon energy and frequency are directly related; as one increases, so does the other.

Frequency

Number of waves that go by in a second; measured in hertz (Hz).

The interaction of ultraviolet light with the skin is an example of which of the following?

Particle: Interactions between ultraviolet light and skin molecules causing change is a particle characteristic.

X-ray's ability to ionize matter is a characteristic of wave or particle?

Particle: When x-rays remove orbital electrons from atoms, it exhibits the physical presence and property characteristics of particles.

Following the concept of the inverse square law, light exhibits characteristics of wave or particle:

Particles Inverse square law reflects changes in intensity or the number of photons striking a given area, which is a particle characteristic.

Waves and particles emitted from unstable nuclei are called:

Radiation The waves and particles from unstable nuclei are both considered radiation: one is electromagnetic (gamma) and the others are particulate (alpha and beta).

A radionuclide refers to atoms with which of the following?

Radioactive nucleus A radionuclide is a term used to describe any atom with a radioactive nucleus.

What is the Curie actually measuring?

Rate of atomic disintegration Although commonly used as a measure of quantity of a radioactive material, the Curie is actually a measure of the number of disintegrations per second or decay.

Initially, physicists thought alpha, beta, and gamma to all be:

Rays Initially, all were thought to be rays, but later experimentation proved alpha and beta to be particles.

Radiopaque

Relatively impenetrable by x-rays or other forms of radiation.

What wave characteristic is the same for all members of the electromagnetic spectrum?

Speed All electromagnetic radiation has the same velocity, the speed of light (3 x 108 m/s).

What is the velocity of electromagnetic radiation?

Speed of Light All electromagnetic radiation has the same velocity, the speed of light (3 x 108 m/s).

Hertz

The SI unit of measurement for frequency (abbreviated Hz); 1 Hz - 1 cycle per second.

Attenuated

The condition in which some electromagnetic radiation photons (such as light or x-rays) are absorbed but some are transmitted through a substance.

Planck's Quantum Theory

The equation for calculating photon energy in electron volts, E=H*F; E (energy) = h (Planck's constant) times f (frequency in hertz).

Amplitude

The height of a wave. A wave with a large amplitude is generally stronger than a wave with a small amplitude

Half-life

The length of time it takes for half the atoms in a given amount of an element to decay; a measure of radioactivity. Half-life is measured in units of curies (Ci) or becquerels (Bq).

Inverse square law

The principle that the intensity of electromagnetic radiation such as light or x-rays diminishes by a factor of the square of the distance from its source.

Radioactive decay

The process by which radionuclides (radioactive atoms) emit particles and energy

Ionization

The process of turning an atom into an ion by adding or removing an electron which changes the electrical charge of the atom.

Electromagnetic spectrum

The range of electromagnetic energy in wavelengths. Every possible electromagnetic frequency from lowest energy to highest, radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma rays.

Refraction is a characteristic of wave or particle?

Wave Refraction, reflection, and transmission are wave characteristics.

Attenuation of x-rays is a characteristic of wave or particle?

Wave: Attenuation is one of the wave characteristics.

Frequency is a characteristic of wave or particle?

Wave: Frequency, wavelength, speed, and amplitude are wave characteristics.

Transmission is a characteristic of wave or particle?

Wave: Refraction, reflection, and transmission are wave characteristics.

Diffraction

a change in direction of waves as they pass through an opening or around an obstacle in their path

Reflection

a change in direction of waves when they bounce off a barrier.

Refraction

a change in the direction of waves as they pass from one medium to another.

Particulate radiation

a stream of atomic or subatomic particles that may be charged positively (e.g. alpha particles) or negatively (e.g. beta particles) or not at all (e.g. neutrons).

The warm feeling of sunlight is a characteristic of wave or particle?

particle

Reflection is a characteristic of wave or particle?

wave

Seeing color is a characteristic of wave or particle?

wave

Xrays being transmitted through substances exhibits characteristics of wave or particle?

wave