The discussion revolves around calculating the electric field and potential difference associated with point charges, specifically focusing on the relationships between voltage, distance, and electric field strength.
Several participants are exploring different interpretations of the problem, particularly regarding the correct application of formulas and the implications of signs in their calculations. Some guidance has been offered regarding the need for careful consideration of physical situations and the proper use of equations.
There are indications of confusion regarding specific distances and the potential difference, as well as the need for further justification of answers based on the physical context of the problem.
That one is correct.WeiLoong said:E=v/d
d=100/800
d=0.125m
By potential at X, the question must refer to the potential difference between point X and the 0 V. So, 0.125+0.4 is not the correct value for the corresponding distance.WeiLoong said:V=Ed
=800(0.125+0.4)
=420V
Just want to remind you, in case you are not yet aware of, that that answer is still missing something to be justified according to the physical situation given in the problem.WeiLoong said:that mean ed = 800x0.40 only?
Write down the formula of electric field due to each charge along the connecting line, define this line as ##x##. Denote ##x_1## and ##x_2## as the distances of a given point from ##Q_1## and ##Q_2##, respectively. The equation you have there is wrong.WeiLoong said:neeed help about 15b.
W= kq/r + kq/r ?
no idea about it.hehe
Yes, it should be -320, otherwise the E field vector cannot be uniform everywhere.WeiLoong said:i guess it should be -320 since V is decreasing.
No, that's still not correct. Please look up "Coulomb's law" either in your book or in the internet.WeiLoong said:Q1= k(40uC)/12cm
There is no "perhaps" in this matter because the related equation which is sometimes called "Coulomb's law" had been agreed upon among the physicists long time ago. You will gain much more knowledge by searching/reading on your own about this basic concept of electric field by a point charge in electrostatics than you will if someone were to explain that to you.WeiLoong said:Perhaps it should be kqq/r