# Ranking the E-field from a graph! alittle confused.

1. Sep 28, 2005

### mr_coffee

Figure 24-27 gives the electric potential V as a function of x.
Figure

(a) Rank the five regions according to the magnitude of the x component of the electric field within them, greatest first (use only the symbols > or =, for example 2=4>1=3>5).

I got the other 2 parts (b) and (c) right. What I thought was, the longer the space is in the x direction the bigger the magntude of the electric field. Which was wrong, i also tried to find the area under of the curve which was also wrong. When I tried to rank them from the area under the curve I got:
3>4=2>1>5
When i ranked them from the length fo the x distance, i got:
4>1=3=5>2

both wrong, what did i do wrong?

2. Sep 28, 2005

### Tom Mattson

Staff Emeritus
$$E=-\frac{dV(x)}{dx}$$

That means that the greater the slope of $V(x)$, the greater the absolute value of $E$.

3. Sep 28, 2005

### mr_coffee

Awesome!! thanks alot!!