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The value of Planck's constant is:

Asked in AIPMT 2002 · Photon energy, momentum and mass

• (1) 6.63×10⁻³⁴ J s⁻¹
• (2) 6.63×10⁻³⁴ kg m² s⁻¹
• (3) 6.63×10⁻³⁴ kg m²
• (4) 6.63×10⁻³⁴ J s

Step-by-step solution

Why the other options are wrong

• (1) comes from divides by the second instead of multiplying: E=h u needs h to turn a per-second into an energy, so the second must be on top
• (2) comes from this is dimensionally the same as the answer, since J s=kg m² s⁻¹, but the paper's key marks the joule-second form; both describe the same quantity
• (3) comes from missing a factor of time entirely; kg m² is a moment of inertia, not an action

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