Question

Which unit of physical quantity remains same for all unit system? (a) meter (b) second (c) ampere (d) kilogram

Short answer

The unit of physical quantity that remains the same for all unit systems is the second (option b).

Step-by-step solution

Evaluate Option (a): Meter

The meter is the basic unit of length in the International System of Units (SI). However, in other unit systems like the British Imperial System, the basic unit of length is the foot. Therefore, the meter does not remain the same for all unit systems.

Evaluate Option (b): Second

The second is the basic unit of time in the International System of Units (SI) and is also used as the unit of time in other unit systems like the British Imperial System. Therefore, the second remains the same for all unit systems.

Evaluate Option (c): Ampere

The ampere is the basic unit of electric current in the International System of Units (SI). However, it may not be used as the unit of electric current in all unit systems. Therefore, the ampere does not remain the same for all unit systems.

Evaluate Option (d): Kilogram

The kilogram is the basic unit of mass in the International System of Units (SI). However, in other unit systems like the British Imperial System, the basic unit of mass is the pound. Therefore, the kilogram does not remain the same for all unit systems.

Conclusion

Based on our assessment of each option, the second (option b) remains the same for all unit systems. Therefore, the correct answer is \( \boxed{\text{(b)} \ \text{second}} \).

Key concepts

Second as Universal Unit

The concept of time is a fundamental aspect of our world, and the second is the universal unit used to measure it. It's the most widely accepted unit across different systems of measurement. Whether you are using the International System of Units (SI), the British Imperial System, or any other standard system, the second remains consistent. This makes it exceptionally useful for scientific calculations, engineering, and everyday activities.

The reason why the second is adopted universally lies in its definition. Based on the periodic phenomena of a certain type of radiation from cesium-133 atoms, it represents an unvarying measure. This atomic basis ensures that the second is globally accurate and reliable, transcending differences in regional measurement practices.

SI Units

SI units, or the International System of Units, are a globally accepted system for measurement that ensures consistency and clarity in scientific communication. As one of the most comprehensive and systematically developed unit systems, it includes seven base units: meter, kilogram, second, ampere, kelvin, mole, and candela.

Within this framework, each base unit corresponds to a fundamental physical quantity such as length, mass, time, electric current, temperature, amount of substance, and luminous intensity. The second is one of these base units, providing a standardized reference that is critical in inter-disciplinary research and technology development. By using SI units, scientists and engineers can easily share data and results, facilitating excellent collaboration across borders.

Unit Systems Comparison

Comparing different unit systems can help highlight why certain units, like the second, hold a universal status. While the International System of Units (SI) is widely used and recognized globally, other systems like the British Imperial and the United States customary systems also exist.

Each of these systems has its own base units and method of measurement. For example, while SI uses meters and kilograms for length and mass, the British Imperial system might use inches and pounds. However, all these systems converge on the second for measuring time, showcasing its adaptability and importance.

• SI System: Utilizes meters, kilograms, seconds, etc.
• British Imperial System: Uses feet, pounds, seconds, etc.

This commonality of the second simplifies tasks such as time conversion, data analysis, and communication between different scientific and engineering communities.

Basic Units of Measurement

Basic units of measurement form the foundation for developing various scientific and practical applications. Each unit corresponds to a dimension of physical phenomena, such as length, mass, or time. These units allow for standardized measurement and interaction with the world around us.

In the realm of basic units, the second is fundamental. Time is a critical variable in nearly all scientific equations and understanding processes in physics, chemistry, and beyond. This universality provides a common language that bridges the gap among various scientific disciplines and cultures.

• Basic Length Unit: Meter in SI, but varies in other systems (e.g., feet in British).
• Basic Mass Unit: Kilogram in SI, but alternatives like pounds exist.
• Basic Time Unit: Second across all recognized unit systems.

These units together form a comprehensive system enabling precise measurement in science, engineering, and daily life.