Derived Planck Units
In any system of measurement, units for many physical quantities can be derived from base units. Table 3 offers a sample of derived Planck units, some of which in fact are seldom used. As with the base units, their use is mostly confined to theoretical physics because most of them are too large or too small for empirical or practical use and there are large uncertainties in their values (see Discussion and Uncertainties in values below).
| Name | Dimension | Expression | Approximate SI equivalent |
|---|---|---|---|
| Planck area | Area (L2) | 2.61223 × 10−70 m2 | |
| Planck volume | Volume (L3) | 4.22419 × 10−105 m3 | |
| Planck momentum | Momentum (LMT−1) | 6.52485 kg m/s | |
| Planck energy | Energy (L2MT−2) | 1.9561 × 109 J | |
| Planck force | Force (LMT−2) | 1.21027 × 1044 N | |
| Planck power | Power (L2MT−3) | 3.62831 × 1052 W | |
| Planck density | Density (L−3M) | 5.15500 × 1096 kg/m3 | |
| Planck angular frequency | Frequency (T−1) | 1.85487 × 1043 s−1 | |
| Planck pressure | Pressure (L−1MT−2) | 4.63309 × 10113 Pa | |
| Planck current | Electric current (QT−1) | 3.4789 × 1025 A | |
| Planck voltage | Voltage (L²MT−2Q−1) | 1.04295 × 1027 V | |
| Planck impedance | Resistance (L2MT−1Q−2) | 29.9792458 Ω |
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