Explanation:
We need to find the speed of an electron that has fallen through a potential difference of 125 volts. It can be calculated using the De-broglie hypothesis as :
(a) V = 125 volts
[tex]\dfrac{1}{2}mv^2=qV[/tex]
Where
v = speed of electron
V is potential difference
[tex]v=\sqrt{\dfrac{2qV}{m}}[/tex]
[tex]v=\sqrt{\dfrac{2\times 1.6\times 10^{-19}\times 125\ V}{9.1\times 10^{-31}}}[/tex]
v = 6629935.44 m/s
[tex]v=6.62\times 10^6\ m/s[/tex]
(b) V = 125 megavolts
[tex]V=1.25\times 10^8\ V[/tex]
[tex]v=\sqrt{\dfrac{2qV}{m}}[/tex]
[tex]v=\sqrt{\dfrac{2\times 1.6\times 10^{-19}\times 1.25\times 10^8\ V}{9.1\times 10^{-31}}}[/tex]
[tex]v=6.62\times 10^9\ m/s[/tex]
Hence, this is the required solution.
