Question

How many fundamental units are there in SI system? (a) 5 (b) 7 (c) 6 (d) 4

Short answer

There are 7 fundamental units in the SI system.

Step-by-step solution

Identify the fundamental units in SI system

The SI system is based on seven fundamental units, which are used to describe various physical quantities. These fundamental units are: 1. Meter (m) - representing length 2. Kilogram (kg) - representing mass 3. Second (s) - representing time 4. Ampere (A) - representing electric current 5. Kelvin (K) - representing temperature 6. Candela (cd) - representing luminous intensity 7. Mole (mol) - representing the amount of substance Counting these fundamental units gives us 7 in total.

Choose the correct answer

Now that we know there are 7 fundamental units in the SI system, we can select the correct response from the given options: (a) 5 (b) 7 (c) 6 (d) 4 The correct answer is (b) 7, as there are 7 fundamental units in the SI system.

Key concepts

Fundamental Units

In the world of science and measurements, it is crucial to have a standard system to express different kinds of quantities. This is where the concept of fundamental units becomes essential. Fundamental units are the basic building blocks that define all other units of measurement. They form the foundation upon which the entire system of measurement is constructed. There are seven fundamental units in the SI system:

• Meter (m) for length
• Kilogram (kg) for mass
• Second (s) for time
• Ampere (A) for electric current
• Kelvin (K) for temperature
• Candela (cd) for luminous intensity
• Mole (mol) for amount of substance

These units are considered 'fundamental' because other units are derived from them. For example, speed is expressed in meters per second (m/s), combining two fundamental units—meter and second. Having these standard units helps scientists and engineers communicate measurements globally without confusion.

Physical Quantities

Physical quantities refer to characteristics of objects or systems that can be measured. They are divided into fundamental quantities, which correspond to the fundamental units, and derived quantities. Physical quantities are represented with numbers and corresponding units. For example, the concept of speed includes a number (such as 20) and a unit (meters per second).

So what makes a quantity physical? It must be something that can be quantified through measurement or calculation, like length, mass, or time. These quantities help us understand the world, letting us describe, analyze, and predict phenomena. For example:

• Length helps us determine the size or distance.
• Mass tells us how much matter is present.
• Time allows us to sequence events.

By using physical quantities, we can express scientific laws and formulas effectively and universally.

SI System

The International System of Units, abbreviated as SI, is the globally accepted metric system of measurement. Established in 1960, the SI system lays down the foundation for scientific measurement by providing a set of standard units for physical quantities. Its comprehensive nature allows for precise and uniform communication across different disciplines and industries.

The SI system is based on the seven fundamental units we've discussed. It is widely used because it ensures consistency and simplicity in scientific data sharing. For any scientific inquiry, precise measurements are necessary, and the SI system offers just that. Thanks to SI units, collaborations and studies across countries are feasible without confusion or conversion errors.

• The SI system helps to maintain around-the-world standardized measurements.
• It fosters clear communication in scientific communities and industries.
• Adopting SI units can greatly simplify data comparison globally.

The beauty of the SI system is in its universality and adaptability, making it an integral part of scientific endeavors and everyday life.