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The de Broglie wavelength of a bullet of mass 0.040 kg travelling at a speed of 1 km s⁻¹ is ______ m.

Asked in GSEB Board July 2021 · de Broglie relation and its graphs

• (1) 1.7×10⁻³⁵
• (2) 4.04×10⁻²⁴
• (3) 1.1×10⁻³²
• (4) 3×10⁻³²

Step-by-step solution

Why the other options are wrong

• (2) No single slip gives 4.04×10⁻²⁴ m. Sanity check: h/(mv) = (6.63×10⁻³⁴)/(40) ≈ 1.7×10⁻³⁵ m.
• (3) No single slip gives 1.1×10⁻³² m; even forgetting to convert 1 km s⁻¹ into 1000 m s⁻¹ gives 1.7×10⁻³² m. Sanity check: (6.63×10⁻³⁴)/(0.040×1000) ≈ 1.7×10⁻³⁵ m.
• (4) No single slip gives 3×10⁻³² m. Sanity check: mv = 0.040×1000 = 40 kg m s⁻¹, and h/(40) ≈ 1.7×10⁻³⁵ m.

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