Question

The energy of an electron is 4.0×10-19 J.Express it in eV.

Answer 1

$1ev = 1.6 \times {10}^{ - 19} j \\ \\ 1j = \frac{1}{1.6 \times {10}^{ - 19} } ev \\ 4 \times {10}^{ - 19} j = \frac{4 \times {10}^{ - 19} }{1.6 \times {10}^{ - 19} } ev \\ 4 \times {10}^{ - 19} j = \frac{40}{16} ev = 2.5ev$
2.5eV






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Answer 2

The energy of an electron is $4\times 10^{-19}\ J=2.5\ eV$

Explanation:

Given that,

The energy of an electron is $4\times 10^{-19}\ J$. It is required to convert the energy of electron from joule to electron volt. Since,

$1\ eV=1.6\times 10^{-19}\ J$

$1\ J=\dfrac{1}{1.6\times 10^{-19}}\ eV$

So,

$4\times 10^{-19}\ J=\dfrac{4\times 10^{-19}}{1.6\times 10^{-19}}\ eV$

Hence, $4\times 10^{-19}\ J=2.5\ eV$

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Energy of an electron

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