Final answer:
The potential difference needed to stop an electron with an initial velocity v = 7.6 × 10^5 m/s is 0 V.
Step-by-step explanation:
The equation that relates potential difference V, kinetic energy KE, and charge q is: KE = qV. To find the potential difference needed to stop the electron, we can equate the kinetic energy of the electron to zero, since it comes to a stop. The equation becomes: 0 = qV. Rearranging the equation, we can solve for V: V = 0/q. Substituting the charge of the electron (q = -1.60 × 10-19 C) into the equation, we get V = 0/(-1.60 × 10-19 C) = 0 V.