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JAMB Physics 2021 Paper

Question : 15

Total: 40

^{16}

Hz, the accelerating potential is?

Solution:

Concept:

The X-ray photon energy equals the kinetic energy given to the electron by the accelerating potential.

Explanation:

The energy of the emitted X-ray is

E = hf

The work done on the electron by the accelerating potential is

E = eV

So,

eV = hf

and

V = \frac{hf}{e}

Substitute the correct values:

h = 6.63 \times 10^{-34} \, \mathrm{J\,s}

f = 1.6 \times 10^{16} \, \mathrm{Hz}

, and

e = 1.6 \times 10^{-19} \, \mathrm{C}

V = \frac{(6.63 \times 10^{-34})(1.6 \times 10^{16})}{1.6 \times 10^{-19}}

V = \frac{1.0608 \times 10^{-17}}{1.6 \times 10^{-19}} = 66.3 \, \mathrm{V}

Answer:

66.3 \, \mathrm{V}

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