Chapter 29 - Potential and Field - Exercises and Problems - Page 863: 14

(a) When $x = 0$:$~~~E_x = 0$ (b) When $x = 1~m$: $~~~E_x = -200~V/m$

(a) We can find $E_x$ when $x = 0$: $E_x = -\frac{dV}{dx}$ $E_x = -(200x)~V/m$ $E_x = -(200)(0)~V/m$ $E_x = 0$ (b) We can find $E_x$ when $x = 1~m$: $E_x = -\frac{dV}{dx}$ $E_x = -(200x)~V/m$ $E_x = -(200)(1)~V/m$ $E_x = -200~V/m$