Question

The graph in the figure shows the variation of the electric potential V(x) (in arbitrary units) as a function of the position x (also in arbitrary units). Which of the choices below correctly describes the orientation of the x-component of the electric field along the x-axis?

A. Ex is positive from x = -2 to x = 0, and negative from x = 0 to x = 2.
B. Ex is negative from x = -2 to x = 0, and positive from x = 0 to x = 2.
C. Ex is negative from x = -2 to x = 2.
D. Ex is positive from x = -2 to x = 2.

Answer 1

@flamin1 We know that
\[E_x=-\frac{dV(x)}{dx}\]
Can you tell me the slope of V(x) from -2 to 0 and 0 to -2?

Answer 2

negative from -2 to 0 and positive from 0 to -2

Answer 3

oh I see that's it

Answer 4

what about the negative sign in the equation

Answer 5

So Ex will be -ve of the slope of V(x)

Answer 6

from -2 to 2?

Answer 7

-2 to 0 Vx 's slope is negative
so Ex is positive
Now you tell me the sign of Ex from 0 to 2?

Answer 8

k got it
just need to flip the signs

Answer 9

that would be negative from 0 to 2

Answer 10

Yes

Answer 11

k thanks alot