Matter & Energy Quiz

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Questions and Answers

Which type of energy is described as the energy of motion at the atomic and molecular level?

Thermal Energy (correct)

Electromagnetic Energy

Electrical Energy

Nuclear Energy

What distinguishes matter from other entities in the physical world?

Volume

Mass (correct)

Weight

Density

Which form of energy is contained within the nucleus of an atom?

Nuclear Energy (correct)

Chemical Energy

Thermal Energy

Mechanical Energy

What type of radiation is NOT considered ionizing radiation?

Ultrasound Signup and view all the answers

Electrical energy is produced when an electron moves through which of the following?

Electrical potential difference Signup and view all the answers

What is the nature of uncharged particles regarding electric fields?

They do not have electric fields. Signup and view all the answers

What does the Law of Conservation of Energy state?

Energy can be transformed but not created or destroyed. Signup and view all the answers

Which of the following describes Coulomb’s Law?

The electrostatic force is directly proportional to the product of charges and inversely proportional to the square of the distance. Signup and view all the answers

Which wavelength range is associated with electromagnetic radiation?

10-10 to 10-14 m Signup and view all the answers

What effect does an electric field have on charged particles?

It causes charged particles to move from one pole to another. Signup and view all the answers

How is the frequency of electromagnetic radiation quantified?

$10^{18}$ to $10^{22}$ Hz Signup and view all the answers

What determines the movement of charged particles in an electric field?

The polarity of the electric field. Signup and view all the answers

What is a characteristic of materials that can be conductive?

They can allow the flow of electric current. Signup and view all the answers

What is a defining characteristic of superconductors?

They have no resistance below a critical temperature. Signup and view all the answers

What is required for a conductor to allow electrons to flow easily?

An applied voltage. Signup and view all the answers

How is electric resistance measured?

In Ohms. Signup and view all the answers

Which of the following substances is an example of an insulator?

Rubber. Signup and view all the answers

What are semiconductors characterized by?

Behaving as insulators or conductors depending on conditions. Signup and view all the answers

What happens to electric current when electric resistance increases?

It decreases. Signup and view all the answers

What does Ohm's Law describe?

The relationship between voltage, current, and resistance. Signup and view all the answers

What distinguishes alternating current from direct current?

The current alternates direction. Signup and view all the answers

What characteristic do conductors and superconductors share?

Both allow electric charge to flow with no resistance. Signup and view all the answers

Which of the following materials demonstrates high resistance, making it an insulator?

Clay. Signup and view all the answers

What is the primary blood cell type affected first within minutes to hours after exposure?

Lymphocytes Signup and view all the answers

What is the total equivalent dose for an embryo fetus for the entire gestation period?

5 mSv Signup and view all the answers

What is the recovery time for granulocytes and thrombocytes after irradiation?

2 months Signup and view all the answers

Which safety principle significantly reduces radiation exposure when positioning shielding?

Shielding Signup and view all the answers

What is the relationship between radiation-induced chromosome aberrations and radiation dose?

Non-threshold dose response Signup and view all the answers

How long does it take for erythrocytes to fully recover after radiation exposure?

6 months to 1 year Signup and view all the answers

What is the thickness of the absorber equivalent to one TVL in reducing radiation intensity?

3.3 cm Signup and view all the answers

What percentage of occupational exposure can protective aprons reduce?

25% Signup and view all the answers

What is the primary function of the high voltage generator in an x-ray system?

To increase the output voltage necessary for x-ray production Signup and view all the answers

Which timing circuit is able to measure time intervals as small as 1 ms?

Electronic Timer Signup and view all the answers

How does the falling load generator minimize exposure time?

By beginning at maximum mA and then decreasing Signup and view all the answers

What role do precision resistors serve in the x-ray system?

To reduce voltage to a level suitable for selected milliamperage Signup and view all the answers

What is the purpose of the Automatic Exposure Control (AEC) in an x-ray system?

To automatically terminate exposure when a predetermined radiation intensity is reached Signup and view all the answers

What does the space charge effect refer to in x-ray production?

Electrostatic repulsion of the electron cloud near the filament Signup and view all the answers

What describes the signal from the MA meter in an x-ray system?

It monitors the x-ray tube current Signup and view all the answers

What is the relationship between the turns ratio and voltage in a transformer?

Directly proportional to voltage and inversely proportional to current Signup and view all the answers

Which component is primarily responsible for converting AC to DC in an x-ray system?

Rectifiers Signup and view all the answers

Which type of semiconductor has loosely bound electrons?

P-type semiconductor Signup and view all the answers

What is the primary limitation of a single-phase power x-ray system?

Results in a pulsating x-ray beam with zero output at some points Signup and view all the answers

What distinguishes a full-wave rectification from half-wave rectification?

It cuts exposure time in half Signup and view all the answers

In a high voltage transformer, how is the secondary current related to the primary current?

Secondary current is less than primary current Signup and view all the answers

What is a primary advantage of using a three-phase power system?

The voltage remains constant during exposure Signup and view all the answers

What is thermionic emission in the context of x-ray production?

The release of electrons from a heated filament Signup and view all the answers

Study Notes

Matter & Energy

Matter is anything that occupies space and has mass.
Mass is the distinguishing characteristic of matter and is measured in kilograms.
Atoms are the building blocks of matter.
Energy is the ability to do work.
Electrical energy is produced when an electron moves through an electrical potential difference.
Thermal energy is the energy of motion at the atomic and molecular level.
Nuclear energy is energy contained in the nucleus of an atom.
Electromagnetic energy (EMR) is radiation and is a transfer of energy.
Ultrasound is a form of radiation but not ionizing radiation.

Laws of Conservation

Law of Conservation of Matter: Matter can neither be created nor destroyed.
Law of Conservation of Energy: Energy may be transformed from one form to another, but cannot be created or destroyed.
Coulomb's Law: The electrostatic force is directly proportional to the product of the electrostatic charges and inversely proportional to the square of the distance between them.
Law of Distribution: Electric charge distribution of charges is uniform throughout or on the surface.

Electrodynamics

The study of electric charge in motion.

Conductors

Substances through which electrons flow easily.
Require voltage to move the electron.
Characteristics:
- Variable resistance
- Obeys Ohm's Law
Examples: Copper, Aluminum, & Water

Insulator

Substances that do not allow electrons to flow.
Characteristics:
- Extremely high resistance
- Necessary with high voltage for insulation (to protect from electrocution)
Examples: Glass, Rubber, & Clay

Semiconductors

Materials that sometimes behave as insulators and sometimes as conductors.
Characteristics:
- Can be resistive
- Can be conductive
- Basis of computers
Examples: Silicon, & Germanium

Superconductor

Materials that allow electrons to flow without resistance.
Characteristics:
- No resistance
- No electrical potential required (voltage)
- Must be very cold/extreme low temperature
Examples: Niobium and titanium

Superconductivity

The property of some matter to exhibit no resistance below a critical temperature.

Electric Circuits

The path of electron flow from the generating source through the various components and back again.

Electric Current/Electricity

Flow of electrons through a conductor.
Direction: Always opposite the electron flow.
Measured in Amperes (A)

Electric Resistance

Measured in ohms.
Increasing electric resistance results in a reduced electric current.

Ohm's Law

The voltage across the total circuit or any portion of the circuit is equal to the current times the resistance.
Formula: V = I x R

Alternating Current (AC)

Electrons flow alternately in opposite directions.
Electrons flow first in a positive direction and then in a negative direction.
Sinusoidal wave.

Magnetism

Oxide of iron (Fe3O4)
A rodlike stone moving back and forth also called as lodestone or leading stone.

Magnetic Field

Any charged particle in motion creates a magnetic field.
Magnetism controls the kVp and operates as an induction device.

High Voltage Generator

Housed in an equipment cabinet positioned against a wall, close to the x-ray tube.
Newer generator designs take up less space.
Reduces patient radiation dose.

Operating Console

Most familiar to the radiologic technologist.
Used to control the x-ray tube current and voltage applied to the xray tube.
Provides control of:
- Line compensation
- kVp
- mA
- Exposure time
Most xray systems are designed to operate on 220v power.

Radiation Quantity (mAs)

Number of x-rays.
Intensity of the x-ray beam.
Controlling factor of current.
High number of electrons, higher heat provided to the x-ray tube.
Units: mR, mGy or mR/mGya, mAs.

Autotransformer Law

States that the voltage received and provided by the transformer is directly proportional to the number of turns.
Vs/Vp = Ns/Np

kVp Meter

Placed across the output terminals of the autotransformer.
Actually reads voltage, not kVp.
Pre-reading kVp meter: Allows the voltage to be monitored before an exposure.

Filament Temperature

Controlled by the filament current, determines the number of electrons emitted by the filament.

Filament Current

Measured in Ampheres (A).
X-ray tube is controlled through a separate circuit called Filament Circuit.
Operates at currents of 3 to 6 Ampere.

Space Charge Effect

Phenomena via electrostatic repulsion.
Electron cloud near the filament.

Thermionic Emission

Release of electrons from a heated filament.

Precision Resistors

Used to reduce the voltage to a value that corresponds to the selected milliamperage.

Falling load generator

Exposure begins at maximum mA, then drops as the anode heats, which results in minimum exposure time.

mA x Exposure Time (mAs)

Product of x-ray tube current (mA) and exposure time is mAs.
Measure of Electrostatic Charge (C).

mA meter

Monitors the x-ray tube current.
Connected at the center of the secondary winding of the high-voltage setup transformer.
Ensures electrical safety.

Filament Transformer

"Filament heating isolation step-down transformer".
Receives the voltage from the mA selector switch.
Steps down the voltage to approx.. 12 v.
Provides current to heat the filament.
Primary winding: Thin copper, 0.5 to 1Ampere, 150v approximately.
Secondary winding: Thick, 5 to 8Ampere, 120 V.

Exposure Timers

Devices that control the duration of x-ray exposure.

Guard Timer

Terminate exposure after a prescribed time (6s).

Synchronous Timer

Motor driven.
Precision device designed to drive a shaft at precisely 60 rev per second.
Cannot be used for serial exposures.

Electronic Timer

Most sophisticated, complicated, and accurate of the x-ray exposure timers.
Allows a wide range of time intervals to be selected and are accurate to intervals as small as 1ms.
Used for rapid serial exposures, suitable for interventional radiology.
Most exposure timers are Electronic.

mAs Timer

Monitors the product of mA and exposure time (Electrostatic Charge – C).
Terminates exposure when the desired mAs value is reached.
Provides the highest safe tube current for the shortest exposure for any mAs selected.

Automatic Exposure Control (AEC)

Device that measures the quantity of radiation that reaches the IR.
Automatically terminates the exposure when the IR has received the required radiation intensity.

Solid-State Detectors (SSD)

Used to check timer accuracy (as short as 1 ms)

High Voltage Generator

Increases the output voltage from the autotransformer to the kVp necessary for x-ray production.
Heat generated is conducted by the oil, which is used primarily for electrical insulation (DIALA V OIL).
Three primary parts:
- High voltage transformer
- Filament transformer
- Rectifiers

High Voltage Transformer

Step Up Transformer.
Secondary Voltage (kVp) > Primary Voltage (V)
Secondary Current (mA) < Primary Current (A)
Secondary Windings > Primary Windings
Voltage waveform: Sinusoidal.

Turns Ratio

Ratio of the number of secondary windings to the number of primary windings.
Example: 500:1 and 1000:1.
Directly proportional to the voltage.
Inversely proportional to the current.

Rectification

Process of converting AC to DC.
X-rays are only produced by the acceleration of electrons from cathode to the anode and cannot be produced by electrons flowing in the reverse direction (Direct Current).

Voltage Rectification

Ensures that electrons flow from cathode to anode only.

Rectifier

Electronic device that allows current to flow in only one direction.

Diode

Electronic device that contains two electrodes.
All diode rectifiers were vacuum tubes called Valve tubes (Replaced by Solid-State Rectifiers made up of Silicon).

Semiconductor

Between Insulator and conductor in the ability to conduct electricity.

P-type Semiconductor

Have loosely bound electrons (free to move).
Have spaces called holes (no electrons).
Holes: As mobile as electrons.

Solid-State P-N Junction

N-type material placed in contact with p-type crystal.
It conducts electricity in only one direction.
Solid-State Diode: A rectifier.

Half-Wave Rectification

Contains 0, 1, or 2 diodes.
Voltage is now allowed to swing negatively during the negative half of its cycle.
Producing 60 x-ray pulses/per second.
Wastes half the supply of power and requires twice the exposure time.

Full-Wave Rectification

Contains at least 4 diodes.
Negative half-cycle corresponding to the inverse voltage is reversed.
120 x-ray pulses/second.
Exposure time is cut in half.
Used in almost all stationary x-ray.

Single-Phase Power

Results in a pulsating x-ray beam.
X-rays produced have a value near zero.
Single Phase Halfwave voltage ripple: 100%
Single Phase Fullwave voltage ripple: 100%
Voltage varies from zero to maximum.

Three-Phase Power

Voltage impressed across the x-ray tube is nearly constant.
6 pulses per 1/60 second.
Voltage never drops to zero during exposure.
Has a disadvantage in terms of its size and cost.
Requires 10-kVp reduction.
6-Pulse voltage ripple: 14%

The X-ray Tube

Special type of diode - contains an anode and cathode.
Converts electrical energy to electromagnetic energy (x-rays).
Formula for single-phase power: (0.7)(mA x kVp)/1000

Hematopoiesis Cell Survival

Exposure to radiation causes a decrease in the number of all types of blood cells in the circulating peripheral blood.
Lymphocytes are the first blood cells to be affected, depleting within minutes to hours after exposure.
Recovery of lymphocyte levels is very slow.
Granulocytes and thrombocytes are depleted 30 days after irradiation and take 2 months to recover.
Erythrocytes are less sensitive to radiation than other blood cells and take 6 months to 1 year to fully recover.

Radiation Dose Limits

Students (over 18 years old) have a dose limit of 50 mSv.
General public has a dose limit of 1 mSv for frequent exposure and 5 mSv for infrequent exposure.
Embryos and fetuses have a total equivalent dose limit of 5 mSv for gestation, or 0.5 mSv per month.

Cardinal Principles of Radiation Safety (STD)

Shielding: Positioning shielding between the radiation source and exposed personnel significantly reduces radiation exposure.
Time: Reducing the duration of exposure to radiation reduces the total radiation dose received.
Distance: Increasing the distance between the radiation source and exposed personnel reduces the intensity of radiation.

Cytogenetics

The study of the genetics of cells (cell chromosomes).
Radiation-induced chromosome aberrations follow a non-threshold dose-response relationship, meaning that any dose of radiation can cause damage.

Radiation Shielding

One TVL (tenth-value layer) is the thickness of absorber that reduces radiation intensity by 90%.
A protective apron containing 0.5 mm of lead is equivalent to 2 HVLs (half-value layers), reducing occupational exposure by 25%.
1 TVL is equivalent to 3.3 HVLs.

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Description

Test your knowledge on the concepts of matter, energy, and their laws of conservation. This quiz covers key principles such as the nature of atoms, different forms of energy, and fundamental scientific laws. Perfect for students studying basic physics.