Electromagnetism

• What is the fundamental force that magnetism results from?

  The motion of a charged atomic particle
• What are the two types of magnetic moments mentioned in the study material?

  Orbital magnetic moment and spin magnetic moment
• What happens to lines of force in a magnetic field?

  They never intersect and form a 3-dimensional force field
• How is flux density measured?

  In Tesla (T) and Gauss (G)
• What is the relationship between permeability and retentivity in magnetic materials?

  The relationship is inverse
• What are the classifications of magnetic materials?

  • Ferromagnetic
  • Paramagnetic
  • Diamagnetic
  • Nonmagnetic
• What did Oersted's experiment demonstrate?

  A relationship between a moving electric charge and magnetism
• What does Fleming’s Right-Hand Generator Rule indicate?

  It pertains to the direction of induced current flow in a generator
• What is the primary function of a generator?

  To convert mechanical energy to electrical energy
• What are the two types of induction mentioned in the study material?

  Mutual induction and self-induction
• What is the efficiency of transformers mentioned in the study material?

  95% efficiency
• What are the types of rectification processes described in the study material?

  • Half-wave rectification
  • Full-wave rectification
• What is thermionic emission?

  The process of liberating electrons from a heated wire filament
• What is the typical material used for the filament in thermionic emission?

  Tungsten
• What are the components of a transformer?

  • Primary coil
  • Secondary coil
  • Magnetic core
• How does the transformer law relate voltage and turns in the coils?

  Voltage induced in the secondary coil is directly related to the number of turns in the secondary coil
• If a transformer has 100 turns in the primary coil and 50 turns in the secondary coil, what is the relationship of the voltages?

  The voltage in the secondary coil is half that of the primary coil
• What are the types of transformer losses mentioned in the study material?

  • Copper loss
  • Hysteresis loss
  • Eddy current loss
• What is the purpose of capacitors in electrical circuits?

  To accumulate and store electrical charge
• What is the unit of capacitance?

  Farad (F)
• How does full-wave rectification differ from half-wave rectification?

  Full-wave rectification uses at least four rectifiers and provides more efficient current
• What is the significance of self-rectification in x-ray tubes?

  It produces a DC waveform that is inefficient for x-ray production
• What are the main components of an x-ray circuit?

  • Low voltage circuit
  • High tension circuit
  • Filament circuit
• What is the primary function of silicon-controlled rectifiers?

  To control the flow of electrical current
• What is the role of inductive reactance in self-induction?

  It affects nearby turns in the coil due to changing magnetic fields
• How does the efficiency of transformers relate to their construction?

  Efficiency is affected by the materials used and design of the transformer
• If a transformer has a primary voltage of 120V and a secondary voltage of 60V, what can be inferred about the turns ratio?

  The turns ratio is 2:1
• What is the primary purpose of a motor?

  To convert electrical energy to mechanical energy
• What is the difference between synchronous and induction motors?

  Synchronous motors turn at the same rate as the armature, while induction motors do not
• How do galvanometers and ammeters differ in their function?

  Galvanometers measure current flow, while ammeters are connected in series to measure potential difference
• What are the two designs of autotransformers?

  • Primary and secondary coils connected in series
  • Single coil on a central core
• What is the primary function of rectifiers?

  To change AC to DC
• What is the significance of the p-n junction in solid-state diodes?

  It acts like a "one-way gate" for current flow
• How does half-wave rectification protect the x-ray tube?

  It employs a single rectifier to prevent damaging current flow
• What are the characteristics of full-wave rectification?

  • Utilizes both phases of AC
  • Provides DC to the x-ray tube
  • Uses at least four rectifiers
• What is the principle behind thermionic emission?

  It involves liberating electrons from a heated filament
• Why is tungsten typically used for filaments in thermionic emission?

  Because it can withstand high temperatures due to its resistance
• How does the heating of the filament relate to thermionic emission?


  Heating causes "boiling off" of electrons, creating an electron cloud
• If an x-ray tube operates at a high temperature, what effect does this have on thermionic emission?

  It increases the number of electrons liberated from the filament