Consider two points in an electric field. The potential at point 1, V_1, is 35 V

Question

Consider two points in an electric field. The potential at point 1, V_1, is 35 V. The potential at point 2, V_2, is 177 V. An electron at rest at point 1 is accelerated by the electric field to point 2. (a) Write an equation for the change of electric potential energy Delta U of the electron in terms of the symbols given. (b) Find the numerical value of the change of the electric potential energy in electron volts (eV). (c) Express v_2, the speed of the electron at point 2, in terms of Delta V, and the mass of the electron m_e. (d) Find the numerical value of v_2 in m/s.

Explanation / Answer

P1:V1 = 35V
P2:V2 = 177V

a)
V12 = V2-V1

U = Q*V12 or Q*(V2-V1)

b)

U = Q*V12 or Q*(V2-V1)
= 1.6*10^-19*(177-35)
= 2.27*10^-17 J

c) V = 1/2*me*v^2

=> v = sqrt(2U/me)
Because of the Law of Conservation of Energy, all energy in the system is conserved; the loss in electric potential energy is converted into kinetic energy
So,v = sqrt(2U/me)

d)
v = sqrt(2*(2.27*10^-17)/(9.109*10^-31))
= 7.06*10^6 m/s

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.