To find the dimensional formula of Planck's constant ($h$), we can use the equation $E = h\nu$, where $E$ is energy and $\nu$ is frequency.

1. Rearrange the formula: $h = \frac{E}{\nu}$
2. Identify Dimensions:

• Energy ($E$): Work done = Force $\times$ Distance. Dimensions = $[ML^2T^{-2}]$.
• Frequency ($\nu$): Inverse of time period. Dimensions = $[T^{-1}]$.

3. Calculate Dimensions of $h$: $[h] = \frac{[ML^2T^{-2}]}{[T^{-1}]} = [ML^2T^{-2 - (-1)}] = [ML^2T^{-1}]$ Alternatively, the unit of Planck's constant is Joule-second ($J\cdot s$). $[J\cdot s] = [ML^2T^{-2}] \times [T] = [ML^2T^{-1}]$ Note: Planck's constant has the same dimensions as Angular Momentum.