What is the speed of a particle of mass 10-27kg whose wavelength is 10-8m. [h...

Physics

JAMB 1999

What is the speed of a particle of mass 10^-27kg whose wavelength is 10^-8m.

[h = 6.63 x 10^-34Js]

A. 6.63ms^-1
B. 66.30ms^-1
C. 663.00ms^-1
D. 6630.00ms^-1

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Correct Answer: Option B

Explanation

Energy of a particle is given by
E = hf = hV/λ (since V = fxλ)
But in terms of mass M, E = ∆MV²
∴ ∆MV² = hV/λ
∆MV = h/λ
∴ V = h/λ∆M
V = 6.63 x 10^-34/(10^-27 x 10^-8)
V = 6.63 x 10^-34/10^-35
V = 6.63 x 10^-34+35
V = 6.63 x 10
V = 66.3ms^-1

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