(a) Find the electric potential difference required to stop an electron (called

Question

(a) Find the electric potential difference required to stop an electron (called a "stopping potential") moving with an initial speed of 1.82 x 107 m/s kv (b) Would a proton traveling at the same speed require a greater or lesser magnitude of electric potential difference? greater lesser equal Explain This answer has not been graded yet. c) Find a symbolic expression or the ratio of the proton stopping potential and the electron stopping potential av v use the following as necessary: m or the mass of p ton and me for the mass of electron.

Explanation / Answer

Ans:-

Given data vi = 1.82*10^7m/s vf = 0

Kinetic energy converted into potential energy

PEf = ½ * me *v^2

      = ½ * 9.11*10^-31 * (1.82*10^7)^2

PEf = 1.51*10^-16

Change in potential v =PEf /qe = 1.51*10^-16/-1.6*10^-19

                                                                =-943.75J/C =- 0.943KJ/C

B ] Magnitude of potential is larger

Mass of proton is greater than mass of electron

Mp= 1.67*10^-27Kg

So PEf is also greater than potential difference is also greater

C]Ve = PEf/q = ½*me*vi^2/qe

Vp =PEf /q = ½*mp *vi^2 / qp

Vp/Ve =(½*mp *vi^2 / qp)/( ½*me*vi^2/qe)

                    = (mp/q)/(me/-q)

                    = - mp/me

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