Question

What are the 22 SI units?

Answer 1

The International System of Units (SI) defines seven base units from which all other units can be derived. However, there are more units that are widely used in scientific and engineering contexts. Here’s a list of the 22 SI units:

### Base Units
1. **Meter (m)** - Unit of length.
2. **Kilogram (kg)** - Unit of mass.
3. **Second (s)** - Unit of time.
4. **Ampere (A)** - Unit of electric current.
5. **Kelvin (K)** - Unit of thermodynamic temperature.
6. **Mole (mol)** - Unit of amount of substance.
7. **Candela (cd)** - Unit of luminous intensity.

### Derived Units with Special Names
8. **Radian (rad)** - Unit of angle.
9. **Steradian (sr)** - Unit of solid angle.
10. **Hertz (Hz)** - Unit of frequency.
11. **Newton (N)** - Unit of force.
12. **Pascal (Pa)** - Unit of pressure.
13. **Joule (J)** - Unit of energy.
14. **Watt (W)** - Unit of power.
15. **Coulomb (C)** - Unit of electric charge.
16. **Volt (V)** - Unit of electric potential.
17. **Farad (F)** - Unit of electric capacitance.
18. **Ohm (Ω)** - Unit of electrical resistance.
19. **Siemens (S)** - Unit of electrical conductance.
20. **Weber (Wb)** - Unit of magnetic flux.
21. **Tesla (T)** - Unit of magnetic flux density.
22. **Henry (H)** - Unit of inductance.

These units form the backbone of the SI system, providing a consistent framework for measuring and expressing quantities in science and engineering.

Answer 2

The International System of Units (SI) defines seven base units, but it also includes derived units, which are combinations of base units. Here are the 22 SI units, including base and derived units:

### **Base Units:**
1. **Meter (m)** - Unit of length
2. **Kilogram (kg)** - Unit of mass
3. **Second (s)** - Unit of time
4. **Ampere (A)** - Unit of electric current
5. **Kelvin (K)** - Unit of thermodynamic temperature
6. **Mole (mol)** - Unit of amount of substance
7. **Candela (cd)** - Unit of luminous intensity

### **Derived Units:**
8. **Hertz (Hz)** - Unit of frequency (1 Hz = 1 s⁻¹)
9. **Newton (N)** - Unit of force (1 N = 1 kg·m/s²)
10. **Pascal (Pa)** - Unit of pressure (1 Pa = 1 N/m²)
11. **Joule (J)** - Unit of energy (1 J = 1 N·m)
12. **Watt (W)** - Unit of power (1 W = 1 J/s)
13. **Coulomb (C)** - Unit of electric charge (1 C = 1 A·s)
14. **Volt (V)** - Unit of electric potential (1 V = 1 W/A)
15. **Farad (F)** - Unit of electrical capacitance (1 F = 1 C/V)
16. **Ohm (Ω)** - Unit of electrical resistance (1 Ω = 1 V/A)
17. **Siemens (S)** - Unit of electrical conductance (1 S = 1/A·Ω)
18. **Weber (Wb)** - Unit of magnetic flux (1 Wb = 1 V·s)
19. **Tesla (T)** - Unit of magnetic flux density (1 T = 1 Wb/m²)
20. **Henry (H)** - Unit of inductance (1 H = 1 Wb/A·s)
21. **Lumen (lm)** - Unit of luminous flux (1 lm = 1 cd·sr)
22. **Lux (lx)** - Unit of illuminance (1 lx = 1 lm/m²)

These units cover a broad range of physical quantities used in science and engineering.