<<–2/”>a href=”https://exam.pscnotes.com/5653-2/”>h2>CGS System of Units
The CGS system, short for Centimeter-Gram-Second, is a system of physical units based on the centimeter (cm) as the unit of length, the gram (g) as the unit of mass, and the second (s) as the unit of time. It was developed in the late 19th century and was widely used in scientific and engineering fields until the mid-20th century.
Origins and Development
The CGS system emerged from the need for a standardized system of units in scientific research. Prior to the 19th century, various units were used in different countries and disciplines, leading to confusion and inconsistencies. In 1874, a committee of the British Association for the Advancement of Science proposed the CGS system as a universal standard.
The CGS system was initially well-received by the scientific community and gained widespread adoption. It was used in many textbooks and research papers, and it played a significant role in the development of modern physics. However, the CGS system had some limitations, particularly in its handling of electromagnetic units.
Units in the CGS System
The CGS system defines a set of fundamental units for various physical quantities, including:
| Quantity | Unit | Symbol |
|---|---|---|
| Length | Centimeter | cm |
| Mass | Gram | g |
| Time | Second | s |
| Force | Dyne | dyn |
| Energy | Erg | erg |
| Power | Erg per second | erg/s |
| Pressure | Barye | Ba |
| Viscosity | Poise | P |
| Surface Tension | Dyne per centimeter | dyn/cm |
Derived Units:
The CGS system also defines derived units for other physical quantities, which are derived from the fundamental units. For example, the unit of velocity is cm/s, the unit of acceleration is cm/s², and the unit of density is g/cm³.
Electromagnetic Units in the CGS System
The CGS system has several different systems of units for electromagnetic quantities, including:
- Electrostatic Units (ESU): Based on Coulomb’s law, where the force between two charges is proportional to the product of the charges and inversely proportional to the square of the distance between them.
- Electromagnetic Units (EMU): Based on Ampère’s law, where the force between two current-carrying wires is proportional to the product of the currents and inversely proportional to the distance between them.
- Gaussian Units: A hybrid system that combines aspects of both ESU and EMU.
The different electromagnetic units in the CGS system can lead to confusion, as they have different values and relationships. For example, the unit of electric charge in ESU is the statcoulomb, while the unit of electric charge in EMU is the abcoulomb.
Advantages and Disadvantages of the CGS System
Advantages:
- Simplicity: The CGS system is relatively simple to understand and use, as it is based on only three fundamental units.
- Historical Significance: The CGS system played a significant role in the development of modern physics and is still used in some specialized fields.
Disadvantages:
- Incompatibility with SI: The CGS system is not compatible with the International System of Units (SI), which is the modern standard system of units.
- Multiple Electromagnetic Systems: The existence of multiple electromagnetic units in the CGS system can lead to confusion and errors.
- Limited Use: The CGS system is no longer widely used in most scientific and engineering fields.
Transition to the SI System
In the mid-20th century, the SI system emerged as the preferred system of units for scientific and engineering applications. The SI system is based on seven fundamental units, including the meter (m) for length, the kilogram (kg) for mass, and the second (s) for time.
The transition from the CGS system to the SI system was gradual but ultimately successful. Today, the SI system is the dominant system of units used in science and engineering worldwide.
Frequently Asked Questions
Q: What is the difference between the CGS system and the SI system?
A: The CGS system is based on the centimeter, gram, and second, while the SI system is based on the meter, kilogram, and second. The SI system is more widely used and is considered the modern standard system of units.
Q: Why is the CGS system no longer widely used?
A: The CGS system has several disadvantages, including its incompatibility with the SI system and the existence of multiple electromagnetic units. The SI system is more consistent and easier to use, making it the preferred system for most applications.
Q: Are there any fields where the CGS system is still used?
A: The CGS system is still used in some specialized fields, such as astrophysics and Nuclear physics. However, the SI system is the dominant system of units in most scientific and engineering disciplines.
Q: How do I convert between CGS units and SI units?
A: Conversion factors can be used to convert between CGS units and SI units. For example, 1 centimeter is equal to 0.01 meters, 1 gram is equal to 0.001 kilograms, and 1 dyne is equal to 10â»âµ Newtons.
Q: What are the advantages of using the SI system?
A: The SI system is more consistent, easier to use, and more widely accepted than the CGS system. It is also compatible with other systems of units, making it easier to communicate scientific results internationally.
Q: Will the CGS system ever be completely abandoned?
A: It is unlikely that the CGS system will be completely abandoned, as it is still used in some specialized fields. However, the SI system is the dominant system of units and is likely to continue to be the preferred system for most applications.