Challenge Questions Ch. 5 Test 3 Flashcards
Define Electric Charge and its unit:
a fundamental property of matter that can be either positive or negative
coulomb
Define Electrodynamics
The study of electric charges in motion
Define Electric Power
The rate at which electrical energy is converted into other forms of energy
Define Electrostatics
The study of electric charges at rest
Define Dipole
a molecule that has two poles, or regions, with opposite charges
Define Electrical induction
The creation of a charged region on a neutral object
Define Magnetic domain:
A region in which the magnetic fields of all atoms are lined up in the same direction
Define Autotransformer
a voltage compensator that corrects for minor fluctuations in the current flowing through the x-ray machine.
Guass:
unit of measurement of a magnetic field
Telsa
SI unit of magnetic field strength
Define Electric Potential
The work done per unit charge in bringing a positive test charge from infinity to that point in the field.
What is the difference between a conductor, a semiconductor, and a superconductor?
Conductor - any substance through which electrons easily flow
Semiconductor - a material that under some conditions
behaves as an insulator and in other
conditions behave as a conductor.
Superconductor - a material to exhibits no resistance below
a critical temperature (Tc)
A radiographic exposure requires 100 mAs. How many electrons is this?
6.3 × 10^17 electrons
Describe three types of transformers:
What are three ways to electrify an object?
By:
Contact
Friction
Induction
List the four laws of electrostatics.
1.) Unlike charges attract; like charges repel;
2.) Coulomb’s Law of electrostatic force;
3.) Electrostatic force follows the inverse square law;
4.) Electric charges are uniformly distributed except at regions of high curvature where they are concentrated.
List three diamagnetic materials.
Wood, water, and plastics
What happens when a bar magnet is heated to a very high temperature?
It loses its magnetic properties
Why is electrification easier in dry Phoenix than in humid Houston?
Humidity allows excess electrons to attach to water molecules in the air.
Where in everyday life might one find an electromagnet?
Automatic door opening devices and other controllers.
Explain how a magnetic domain can cause an object to behave like a magnet.
When acted on by an external magnetic field such as the Earth for example, randomly oriented dipoles align with the magnetic field
Describe an electromagnet
Electromagnets consist of wire wrapped around a ferromagnetic core, and when an electric current is conducted through the wire, a magnetic field is created. The intensity of the magnetic field is proportional to the electric current. The ferromagnetic core greatly increases the intensity of the magnetic field.
List three principal types of magnets:
Naturally occurring magnets
Artificially induced magnets (typically produced by aligning their domains in the field of an electromagnet), and Electromagnets (consist of wire wrapped around a ferromagnetic core, and when an electric current is conducted through the wire, a magnetic field is created).
What is the role of magnetism in the study of x-ray imaging?
magnets are used to precisely control the electron beam within an X-ray tube
What should the primary current in the previous question to produce a secondary current of 100 mA.
100 Amps
A coil of wire is called ____
a solenoid
