sorry i cant understand your explainaton in post #399... would you mind to explain based on the photo attached on post#396?

Could you circle the part that you don't particularly understand? It helps me to narrow down my focus on your cognitive problem in the Electricity topic. Thanks!

kindly refer to the photo attached in post #396, i dont understand
for the charge +5e and -3e, the neutral point is at the right side of charge -3e

for the another photo, i dont understand the point where v=0, is located at the centre...

based on my understanding, i think the e(electric potential ) should acted in opposite direction so the forces can cancel each other , thus the point can be called as neutral point where v=0..

correct me if my concept is wrong...

Infinity? or n/2 (1+n)

This post has been edited by Flame Haze: Dec 24 2013, 12:22 AM

Thanks for pointing out! It would be meaningless if the sum to infinity because the series diverges. Just find the formula of the sum up to a finite n positive integer.

This post has been edited by Critical_Fallacy: Dec 24 2013, 12:22 AM

Previous post

Your basic concept is correct, except the “center” position. “Center” means the point is equally distant from the positively charged particle and from the negatively charged particle . The electric potential is zero ONLY when at the center of an electric dipole (a pair of electric charges of equal magnitude but of opposite sign or polarity).

Refer to the figure on Post #399 or #396, now do this for me:

(1) Find the electric potential at the point β (far right) due to a positively charged particle , separated by a distance .

(2) Find the electric potential at the point β (far right) due to a negatively charged particle , separated by a distance .

(3) Find the net electric potential at the point β (far right) due to both charged particles.

(4) Equate the net electric potential V = 0, and then simplify the equation in terms of ratio rA / rB.

This post has been edited by Critical_Fallacy: Dec 24 2013, 12:34 AM

You are good!

her's my ans... i'm not very sure


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Solving physics problems demand concentration. Find Electric Potential V, NOT Electric Field E.

How about your answer for No.4?

You can use the Coulomb's constant, for simplification.

This post has been edited by Critical_Fallacy: Dec 24 2013, 01:00 AM

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Hi delsoo,

There is a mistake.

(1) Find the electric potential at the point β (far right) due to a positively charged particle , separated by a distance .

You can use the Coulomb's constant, for simplification.



This post has been edited by Critical_Fallacy: Dec 24 2013, 01:05 AM

sorry i used to used to use 1/4pi e .... btw the rest are correct? i'm not very sure about my ans for ques 2..

This post has been edited by delsoo: Dec 24 2013, 01:08 AM

It's your preference. To answer the rest, please concentrate on reading my post CLOSELY.

As mentioned in previous post. There is a mistake in (1), which is affecting (3) and (4).

(1) Find the electric potential at the point β (far right) due to a positively charged particle , separated by a distance .

You can substitute the positively charged particle = 5q and the negatively charged particle = -3q, as in your original problem in Post #396.

This post has been edited by Critical_Fallacy: Dec 24 2013, 01:18 AM

so the ans for 1 should be q+/4(pi)9e)(r of A ) ?

Doesn't this figure tell you the whole story clearly?

, thanks again for spending your time to answer my doubts

When solving physics problem, you cannot rush. Read carefully and understand what are required by the questions. They are your mini tasks, sub-problems that you need to tackle.

Looks tough but its not. In fact, its quite easy.
Its actually 1+2+3+…+n So the sum of the series is n(n+1)/2.

Oh. Flame Haze has answered this question XD

This post has been edited by crazywing26: Dec 24 2013, 09:17 AM

Easy is GOOD! Try the next one.