(a) Find the potential difference ?Ve required to stop an electron (called a \"s

Question

(a) Find the potential difference ?Ve required to stop an electron (called a "stopping potential") moving with an initial speed of 2.22 X 10^7 m/s.
= ____________kV

(b) Would a proton traveling at the same speed require a greater or lesser magnitude potential difference? Explain.

(c) Find a symbolic expression for the ratio of the proton stopping potential and the electron stopping potential, ?Vp/?Ve. The answer should be in terms of the proton mass mp and electron mass me.

?Vp/?Ve = _________________

Explanation / Answer

(a). Initial speed v = 2.22 x 10 7 m / s Required potential difference V = ? We know Vq = ( 1/ 2) mv 2                     V = ( 1/2q) mv 2 Where q = charge of electron                = 1.6 x 10 -19 C             m = mass of electron                 = 9.11 x 10 -31 kg Substitue values we get V = 1403 volt (b).Proton mass is higher than electron. So,proton requires greater potential difference. (c). The ratio of the proton stopping potential and the electron stopping potential is         (V p / V e ) = [( 1/2q) m p v 2 ] / [( 1/2q) m e v 2]                           = m p v 2 / m e v 2 If speed v is same than ,  (V p / V e ) = m p / m e If speed v is same than ,  (V p / V e ) = m p / m e

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