Question

15(b) [Energy level diagram, n2=-2.0eV, n0=-12.0eV] If an excited electron moves from n2 to n0, calculate the: (i) frequency; (ii) wavelength of the emitted radiation. [h=6.6x10⁻³⁴Js; 1eV=1.6x10⁻¹⁹J; C=3.0x10⁸ms⁻¹]

Accepted Answer

Energy level of n2=-2.0eV; Energy level of n0=-12.0eV. Energy change as it moves from n2 to n0 = E20 = E2-E0 = -2-(-12) = 10eV.
(i) E=hf. f=E/h = (10x1.602x10⁻¹⁹)/(6.63x10⁻³⁴) = 2.42x10¹⁵ Hz.
(ii) c=λf; λ=c/f = (3x10⁸)/(2.42x10¹⁵) = 1.24x10⁻⁷ m.

WAEC Physics 2010 Theory — Question 11

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