A proton moves along the x-axis where some arrangement of charges has produced the potential V(x)=Vosin(2πx/λ),where Vo = 3800 V and λ = 1.0 mm. a) What minimum speed must the proton have at x = 0 to move down the axis without being reflected? b) What is the maximum speed reached by a proton that at x = 0 has the speed you calculated in part A?

Respuesta :

Answer with Explanation:

We are given that

[tex]V(x)=Vsin(\frac{2\pi x}{\lambda})[/tex]

[tex]V_0=3800 V,\lambda=1.0 mm[/tex]

a.At x=0

V(0)=0

Maximum potential, [tex]V_{max}=V_0=3800 V[/tex]

The proton must have minimum speed  when V(x) is maximum

Initial kinetic energy =[tex]q\Delta V[/tex]

[tex]\frac{1}{2}mv^2=q(V_{max}-V(0))=q(3800-0)=3800q[/tex]

q=[tex]1.6\times 10^{-19} C[/tex]

[tex]m=1.67\times 10^{-27} Kg[/tex]

[tex]v^2=\frac{2\times 3800 q}{m}=\frac{3800\times 2\times 1.6\times 10^{-19}}{1.67\times 10^{-27}}[/tex]

[tex]v=\sqrt{\frac{2\times 3800 q}{m}}=\sqrt{\frac{3800\times 2\times 1.6\times 10^{-19}}{1.67\times 10^{-27}}}[/tex]

[tex]v=8.5\times 10^5 m/s[/tex]

b.The maximum speed reached by a proton when V(x) is minimum

[tex]V_{min}=-3800 V[/tex]

[tex]v=\sqrt{\frac{2q(V_{max}-V_{min}}{m}}[/tex]

[tex]v=\sqrt{\frac{2\times 1.6\times 10^{-19}(3800-(-3800))}{1.67\times 10^{-27}}[/tex]

[tex]v=1.21\times 10^6 m/s[/tex]