Solved: PHYSICS Question for NEET

NEET PHYSICSEasy

The value of Planck's constant is

6.63 × 10⁻³⁴ J-sec

6.63 × 10³⁴ J/sec

6.63 × 10⁻³⁴ kg-m²

6.63 × 10³⁴ kg/sec

Definition: Planck's constant ( $h$ ) relates the energy of a photon ( $E$ ) to its frequency ( $\nu$ ) via the equation $E = h\nu$ .
Value: The accepted value of Planck's constant is approximately $6.626 \times 10^{-34}$ J s , , , . In the context of the question, this is rounded to $6.63 \times 10^{-34}$ .
Units: Rearranging the equation to $h = E/\nu$ , the units are Energy $\times$ Time (since frequency is $1/\text{Time}$ ). The SI unit of energy is Joule (J) and time is Second (s). Therefore, the unit is Joule-second (J s or J-sec) .
Dimensional Analysis: The dimensional formula is $[ML^2T^{-1}]$ , which corresponds to the unit $kg \cdot m^2 \cdot s^{-1}$ . Option C ( $kg\cdot m^2$ ) is dimensionally incorrect as it lacks the per second ( $s^{-1}$ ) factor.
Conclusion: The correct value and unit combination is $6.63 \times 10^{-34}$ J-sec.

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