Electric field vs. Electric potential

[wave41]

Hello everyone...I need help to start on a problem which states that V(r) =V(o) r^2/2R^2...I neeed to find E(r) when R and V(o) are constants...so from defention E= dV/Dr? This is the part I am not sure how to move on..I have to integrate the equation they gave me keeping the V(o) and R as constants?
Thank you...

 

[cookiemonster]

E = \frac{d}{dr}V(r)

V(r) is given, so you get

E = \frac{d}{dr}\left(V_0 \frac{r^2}{2R^2} \right)

So what's the problem?

cookiemonster

 

[wave41]

The problem is that I have a very bad math backround...I am asking if I have to integrate that? Keeping V(o) and R outside the integral...I have not done integrals yet so I am having trouble with it...I have missed math (meaning didn't study it ) from basically 4th grade to 9th so to catch up on it takes me a while...

 

[cookiemonster]

E is defined as the derivative of V. You have V. You'd then have to differentiate V to get E.

There are no integrals involved.

Now, if you had E and you were asked to find V, then you'd have to integrate. But it's the other way around, hence differentiate.

The problem is asking you to evaluate the derivative I described above.

cookiemonster

 

[wave41]

thank you