Study Notes on Resistance in Conductors and Inductors

Definition of Resistance

• Resistance is defined as the force that opposes the flow of electric current in a conductor.

Resistance in Inductors

• In inductors, resistance refers to the ability of a substance to resist the flow of electricity through it.

Conductors and Insulators

• Materials are classified based on their resistance to electric flow:
  • Good Conductors:
  • Have low resistance.
  • Allow electric current to flow easily.
  • Poor Conductors or Insulators:
  • Have high resistance.
  • Do not allow current to flow easily.

Most Effective Conductors

• Among various materials, silver is noted to offer the least resistance to electric current for a given dimension.
  • Limitations of Silver:
  • Silver is too expensive for everyday use in electrical applications.

Alternative to Silver

• Due to the cost of silver, copper is the next best alternative and is commonly used in:
  • Electrical cables.
  • Connecting wires in electric circuits.
  • Applications that require low resistance.

Special Alloys for Specific Resistance Needs

• In cases where resistance must be deliberately increased, special alloys are used. These alloys include:
  • Constantan: A copper-nickel alloy that offers stable resistance over a wide range of temperatures.
  • Manganin: A copper-manganese-nickel alloy used for accurate measurements because of its low temperature coefficient of resistance.
  • Nycrum: An alloy typically used for its high resistivity and stability in various conditions.

Applications of Resistance Modification

• These special alloys are typically used in applications where:
  • Reduced current is required in a circuit.
  • Consistent and minimal variation in resistance is necessary for precision measurements.