# 1 Lecture

## International System of Units

The International System of Units (SI) is the modern form of the metric system and is used in many fields of science, including circuit theory.

## Important Mcq's Midterm & Finalterm Prepration Past papers included

What is the base unit of length in the International System of Units (SI)?

A) Meter

B) Second

C) Kelvin

D) Mole

What is the base unit of mass in the International System of Units (SI)?

A) Kelvin

B) Second

C) Kilogram

D) Candela

What is the base unit of time in the International System of Units (SI)?

A) Kelvin

B) Second

C) Ampere

D) Candela

What is the base unit of electric current in the International System of Units (SI)?

A) Ampere

B) Kelvin

C) Mole

D) Candela

What is the base unit of temperature in the International System of Units (SI)?

A) Ampere

B) Kelvin

C) Mole

D) Candela

What is the base unit of amount of substance in the International System of Units (SI)?

A) Kelvin

B) Mole

C) Second

D) Candela

What is the base unit of luminous intensity in the International System of Units (SI)?

A) Ampere

B) Kelvin

C) Mole

D) Candela

What is the prefix for the value 1/1,000 in the International System of Units (SI)?

A) Micro

B) Milli

C) Kilo

D) Mega

What is the prefix for the value 1,000,000 in the International System of Units (SI)?

A) Micro

B) Milli

C) Kilo

D) Mega

What is the prefix for the value 1,000,000,000 in the International System of Units (SI)?

A) Giga

B) Nano

C) Tera

D) Pico

## Subjective Short Notes Midterm & Finalterm Prepration Past papers included

What is the International System of Units (SI)?

Answer: The International System of Units (SI) is the modern form of the metric system, which is the standard system of measurement used worldwide.

What are the seven base units of the SI?

Answer: The seven base units of the SI are meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), mole (mol), and candela (cd).

What is the meter and what is it used for?

Answer: The meter is the SI unit of length and is defined as the distance traveled by light in a vacuum during a specific time interval. It is commonly used to measure distances or lengths.

What is the kilogram and what is it used for?

Answer: The kilogram is the SI unit of mass and is defined as the mass of a specific physical prototype made of platinum-iridium alloy. It is commonly used to measure the mass of objects.

What is the second and what is it used for?

Answer: The second is the SI unit of time and is defined as the duration of 9,192,631,770 cycles of the radiation corresponding to the transition between two energy levels of the cesium-133 atom. It is commonly used to measure time intervals.

What is the ampere and what is it used for?

Answer: The ampere is the SI unit of electric current and is defined as the constant current that, if maintained in two parallel conductors of infinite length, of negligible circular cross-section, and placed one meter apart in a vacuum, would produce a force between these conductors of 2 × 10?7 newton per meter of length. It is commonly used to measure electrical current.

What is the kelvin and what is it used for?

Answer: The kelvin is the SI unit of temperature and is defined as the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. It is commonly used to measure temperature.

What is the mole and what is it used for?

Answer: The mole is the SI unit of amount of substance and is defined as the amount of a substance that contains as many elementary entities (such as atoms, molecules, ions, or electrons) as there are atoms in 0.012 kg of carbon-12. It is commonly used to measure the amount of a substance in chemistry.

What is the candela and what is it used for?

Answer: The candela is the SI unit of luminous intensity and is defined as the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 × 1012 Hz and that has a radiant intensity in that direction of 1/683 watt per steradian. It is commonly used to measure the brightness of light sources.

Why is the SI important?

Answer: The SI is important because it provides a standardized system of measurement that can be used globally, which facilitates communication and collaboration in science, engineering, and industry. The SI also enables accurate and precise measurements, which are essential for scientific research, technological innovation, and quality control in manufacturing.

### International System of Units

The International System of Units (SI) is the modern form of the metric system and is used in many fields of science, including circuit theory. The SI was first established in 1960 by the General Conference on Weights and Measures (CGPM) and has been updated several times since then. The SI defines a set of seven base units, from which all other units can be derived. In this article, we will discuss the seven base units of the SI and how they are used in circuit theory. The first base unit of the SI is the meter (m), which is the unit of length. In circuit theory, the meter is used to measure the physical dimensions of components such as wires, resistors, and capacitors. The meter is also used to measure the length of transmission lines and the wavelength of electromagnetic waves. The second base unit is the kilogram (kg), which is the unit of mass. In circuit theory, the kilogram is used to measure the mass of components such as transformers, power supplies, and motors. The third base unit is the second (s), which is the unit of time. In circuit theory, the second is used to measure the time it takes for a signal to propagate through a circuit or for a component to switch from one state to another. The fourth base unit is the ampere (A), which is the unit of electric current. In circuit theory, the ampere is used to measure the current flowing through a circuit. This is particularly important for analyzing the behavior of resistors, capacitors, and inductors. The fifth base unit is the kelvin (K), which is the unit of temperature. In circuit theory, the kelvin is used to measure the temperature of components such as transistors, diodes, and integrated circuits. Temperature is an important factor that affects the performance and reliability of electronic components. The sixth base unit is the mole (mol), which is the unit of amount of substance. In circuit theory, the mole is used to measure the number of atoms or molecules in a component or material. This is important for analyzing the behavior of semiconductors and other materials used in electronic devices. The seventh and final base unit is the candela (cd), which is the unit of luminous intensity. In circuit theory, the candela is used to measure the brightness of light emitting diodes (LEDs) and other light sources used in electronic devices. In addition to the seven base units, the SI also defines a set of derived units that can be obtained from the base units. For example, the unit of electric charge is the coulomb (C), which is defined as the amount of charge carried by one ampere of current flowing for one second. The unit of electric potential is the volt (V), which is defined as one joule per coulomb. The unit of resistance is the ohm (?), which is defined as one volt per ampere. In circuit theory, the SI units are used to express various quantities such as voltage, current, power, and energy. By using a consistent set of units, engineers and scientists can communicate their results effectively and make accurate measurements. In addition, the SI units facilitate international trade and commerce by providing a common language for expressing scientific and technical information. In conclusion, the International System of Units (SI) is a standardized system of measurement used in circuit theory and many other fields of science. The SI defines a set of seven base units from which all other units can be derived. The use of SI units ensures consistency and accuracy in scientific and technical measurements, and facilitates international communication and trade.