Question

uniform electric field of magnitude 365 N/C pointing in the positive x-direction acts on an electron, which is initially at rest. The electron has moved 3.00 cm. (a) What is the work done by the field on the electron? 1.753e-18 J (b) What is the change in potential energy associated with the electron? J

Answer 1

Answer:

a)   W = - 1.752 10⁻¹⁸ J,  b)    U = + 1.752 10⁻¹⁸ J

Explanation:

a) work is defined by

         W = F . x

the bold letters indicate vectors, in this case the force is electric

         F = q E

we substitute

         F = q E x

the charge of the electron is

         q = - e

         F = - e E x

let's calculate

         W = - 1.6 10⁻¹⁹  365  3 10⁻²

         W = - 1.752 10⁻¹⁸ J

b) the change in potential energy is

          U = q ΔV

the potential difference is

          ΔV = - E. Δs

 

we substitute

         U = - q E Δs

the charge of the electron is

           q = - e

          U = e E Δs

we calculate

           U = 1.6 10⁻¹⁹ 365  3 10⁻²

           U = + 1.752 10⁻¹⁸ J