Electron accelerated by potential difference

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An electron accelerated by a potential difference of 100V gains kinetic energy proportional to the voltage applied. When the voltage is increased to four times, the kinetic energy becomes four times greater, but the final speed does not increase by the same factor. Instead, the relationship between kinetic energy and speed shows that the final speed is actually doubled. This is derived from the equations relating energy and speed, confirming that the increase in voltage leads to a square root relationship in speed. Thus, doubling the speed occurs with a fourfold increase in voltage.
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An electron is accelerated by a potential difference of, say, 100V. How much greater would its final speed be if it were accelerated with four times as much voltage?
 
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The corresponding energy is eV where e is the elementary charge and v is the applied potential. Note that this energy is kinetic in nature and therefore equal to 1/2mv²

regards
marlon
 
Ep=Ek
eV=1/2mv²
so...four times as much voltage= 16 times greater speed?
 
So if the potential is 4 times bigger then the kinetic energy will get four times bigger. If A = mv²/2 or v = sqrt(2A/m) ; well then after the increase : 4A = mv²/2 or mv² =8A or v = sqrt(8a/m). Now if you divide sqrt(8A/m) by sqrt(2A/m) you acquire : sqrt(4) = 2. So the speed would be doubled...you see

regards
marlon
 
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