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In the Davisson-Germer experiment, an electron emitted from the filament is accelerated through a voltage V. The de Broglie wavelength of that electron will be ______ m. Here m and e are the mass and charge of the electron.

Asked in GUJCET 2017 · Accelerated through a potential difference

Answer: (4) h/(√2Vem)

Step-by-step solution

Idea: accelerating through V gives the electron kinetic energy K = eV.

Momentum from kinetic energy: K = (p²)/(2m), so p = √2mK = √2meV.

De Broglie wavelength: λ = h/p = h/(√2meV)

Check: for V = 100 V this gives about 1.23×10⁻¹⁰ m, the familiar value.

So λ = h/(√2Vem), the same product 2meV written in a different order.

Why the other options are wrong

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