Key learnings:
- The article’s title is: “High Resistivity or Low Conductivity Conducting Material” I will make sure any topics within this title are covered in the “Five Key Learnings Summary”. So here the dot points should explicitly cover: “High Resistivity Conducting Material” “Low Conductivity Conducting Material” Ten Key Takeaways High Resistivity Definition: High resistivity materials resist the flow of electric current, making them essential for certain electrical applications. Key Properties: High resistivity materials must have a high melting point, mechanical strength, ductility, corrosion resistance, flexibility, and be cost-effective and durable. Examples: Common high resistivity materials include tungsten, carbon, nichrome (Brightray B), nichrome V (Brightray C), and manganin. Tungsten: Known for its high melting point, hardness, and tensile strength, tungsten is used in light bulb filaments and X-ray tube electrodes. Carbon: Carbon is versatile in electrical engineering, used in resistors, brushes for DC machines, and electrodes for furnaces and arc lighting. Nichrome (Brightray B): This alloy has high oxidation resistance and is used in electric irons and tubular heaters. Nichrome V (Brightray C): Similar to Nichrome but with a slightly different composition, used in heating elements for electric heaters and furnaces. Manganin: Known for its low temperature coefficient of resistance, manganin is used in heating elements and measuring instruments. Applications of Tungsten: Due to its high resistance to destructive forces, it is used in electrical contacts in addition to filament and electrode applications. Applications of Carbon: It is widely used in making pressure-sensitive resistors, battery cell elements, and components for telecommunication equipment. Five Key Learnings Summary Key learnings: High Resistivity Materials Definition: High resistivity materials are defined as substances that resist the flow of electric current, making them useful in various electrical engineering applications.
- Key Properties: These materials must have high melting points, mechanical strength, ductility, corrosion resistance, and flexibility.
- Examples of High Resistivity Materials: Common examples include tungsten, carbon, nichrome, and manganin.
- Uses of Tungsten: Tungsten is used for light bulb filaments, X-ray tube electrodes, and electrical contacts due to its high melting point and tensile strength.
- Uses of Carbon: Carbon is used in resistors, brushes for DC machines, electrodes for furnaces, and components for telecommunication equipment.
Materials with high resistivity or low conductivity are essential for certain electrical engineering products. They are used to make filaments for incandescent lamp, heating elements for electric heaters, furnaces, space heaters, and electric irons.
Required Properties in High Resistivity or Low Conductivity Conducting Material
The following properties are required in high resistivity or low conductivity conducting material–
- High resistivity.
- High melting point.
- High mechanical strength.
- High ductility, so that can be drawn in the form of wire easily.
- High corrosion resistance mean free from oxidation.
- Low cost.
- Long life or durable.
- High flexibility.
Some of Materials having High Resistivity or Low Conductivity are listed below
- Tungsten
- Carbon
- Nichrome or Brightray B
- Nichrome V or Brightray C
- Manganin
Tungsten
Tungsten is made through complex processes from rare ores or tungstic acids. Here are some key facts about tungsten:
- Very hard.
- Resistivity is twice to aluminum.
- High tensile strength.
- Can be drawn in the form of very thin wire.
- Oxidize very quickly in the presence of oxygen.
- Can be used up to 2000oC in the atmosphere of inert gases (Nitrogen, Argon etc.) without oxidation.
Properties of Tungsten
Properties of tungsten are listed below-
- Specific weight : 20 gm/cm3
- Resistivity : 5.28 µΩ -cm
- Temperature coefficient of resistance : 0.005 / oC
- Melting point : 3410oC
- Boiling point : 5900oC
- Thermal coefficient of expansion: 4.44 × 10-9 / oC
Uses of Tungsten
- Used as filament for incandescent lamp.
- As electrode in X- ray tubes.
- The great hardness, high melting and boiling points make it suitable for use as electrical contact material in certain applications. It is having high resistance for destructive forces produces during operation of electrical contacts.
Carbon
Carbon is widely used in electrical engineering. Electrical carbon materials are made from graphite and other forms of carbon.
Properties of Carbon
- Resistivity : 1000 – 7000 µΩ – cm
- Temperature coefficient of resistance : – 0.0002 to – 0.0008 /oC
- Melting point : 3500oC
- Specific gravity : 2.1gm /cm3
Uses of Carbon
Carbon is having following applications in electrical Engineering
- It is used to make pressure-sensitive resistors for automatic voltage regulators.
- Used for manufacturing the carbon brushes, which are used in DC machines. These carbon brushes improve the commutation as well as reduce the wear and tear.
- For making filament of incandescent lamp.
- For making electrical contacts.
- For making resistors.
- For making battery cell elements.
- Carbon electrodes for electric furnaces.
- Arc lighting and welding electrodes.
- Component for vacuum valves and tubes.
- For makings parts for telecommunication equipment.
Nichrome or Brightray B
Composition of Nichrome or Brightray B
Properties of Nichrome or Brightray B
- Resistivity : 1.10 µΩ -cm
- Temperature coefficient of resistance : 0.0002 /oC
- Melting point : 1350oC
- Specific gravity : 8.24 gm /cm3
- High resistance to oxidation
Uses of Nichrome or Brightray B
Used in making tubular heaters and electric irons.
Nichrome V or Brightray C
Composition of Nichrome V or Brightray C
Properties of Nichrome V or Brightray C
- Resistivity : 40 µΩ – cm
- Temperature coefficient of resistance : 0.0001 /oC
- Melting point : 1400oC
- Specific gravity : 8.4gm /cm3
- High resistance to oxidation
Uses of Nichrome V or Brightray C
Used in making heating elements for electric heaters and furnaces.
Manganin
Composition of Manganin
Properties of Manganin
- Resistivity : 40 µΩ -cm
- Temperature coefficient of resistance : 0.0001 /oC
- Melting point : 1400oC
- Specific gravity : 8.4gm /cm3
- High resistance to oxidation
Uses of Manganin
Manganin has the following applications in electrical Engineering:
- Used in making electric heating elements and in electric furnaces.
- As the manganin is having very low temperature coefficient of resistance, therefore it is used to make the standard resistances and in measuring instruments.
