Half-life = 0.693 ÷ Decay constant
Put in the dimensions of each part: 1 ÷ [T⁻¹] = [T].
The SI unit of half-life is second (s).
These quantities have exactly the same dimensions, a favourite trick in JEE and NEET "which pair has the same dimensions" questions:
Can you get today's formula in one try?Play MLT, the free daily dimensional formula game| Quantity | Formula |
|---|---|
| Planck's constant | [M L2 T−1] |
| Specific charge | [M−1 T A] |
| Work function | [M L2 T−2] |
| Rydberg constant | [L−1] |
| Decay constant | [T−1] |
| Activity | [T−1] |