A quantity f is given by

Question:

A quantity $f$ is given by $f=\sqrt{\frac{h c^{5}}{\mathrm{G}}}$ where $\mathrm{c}$ is speed of light

$\mathrm{G}$ universal gravitational constant and $h$ is the Planck's constant. Dimension of $f$ is that of:

  1. area

  2. energy

  3. momentum

  4. volume


Correct Option: , 2

Solution:

(2) Dimension of $[h]=\left[M L^{2} T^{-1}\right]$

$[\mathrm{C}]=\left[L T^{-1}\right]$

$[G]=\left[M^{-1} L^{3} T^{-2}\right]$

Hence dimension of

$\left[\sqrt{\frac{h C^{5}}{G}}\right]=\frac{\left[M L^{2} T^{-1}\right] \cdot\left[L^{5} T^{-5}\right]}{\left[M^{-1} L^{3} T^{-2}\right]}$

$=\left[M L^{2} T^{-2}\right]=$ energy

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