Problem 27.42 An electron has a de Broglie wavelength: = 3.5×10^10 m h=6.626×10^

Question

Problem 27.42 An electron has a de Broglie wavelength:

= 3.5×10^10 m

h=6.626×10^34 Js

e=1.602×10^19 C

me=9.109×10^31 kg

Part A What is its momentum? Express your answer to two significant figures and include the appropriate units. p = ________

Part B What is its speed? Express your answer to two significant figures and include the appropriate units. v = __________

Part C What voltage was needed to accelerate it from rest to this speed? Express your answer to two significant figures and include the appropriate units. V = _______

Thanks for your help!

Explanation / Answer

A) p = h/

p = (6.626×10^34)/ (3.5×10^10)

p = 1.89 * 10^-24 kgm/s.

B) p = mv

1.89*10^-24 = (9.1*10^-31)v

v =2.077*10^6 m/s

C) From conservation of enenrgy

K.E = P.E

(1/2)mv^2 = eV

0.5*9.1*10^-31*(2.077*10^6)^2 = 1.6*10^-19*V

V =12.3 V

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