The electrical potential function for an electrical field directed parallel to the x - axis is shown in (Fig. 3.152).
.
The magnitude of the electric field in the x - direction in the interval `4 le x le 8` is

Options

A. `2.5 NC^-1`
B. `5 NC^-1`
C. `-2.5 NC^-1`
D. `-5 NC^-1`

Answer

B

Explanation

`E_(r)=-(DeltaV)/(Deltar), E_(x)=-(DeltaV)/(Deltax)`
For `-2 le x le 0, E_(x)=-((10-0))/([0-(-2)])=-5 NC^(-1)`
For `0 le x le 2, E_(x)=0`
For `2 le x le 4, E_(x)=-([20-10])/([4-2])=-5 NC^(-1)`
For `4 le x le 8, E_(x)=-([0-20])/([8-4])=5 NC^(-1)`