Does there exist electric field around all the substances? - Physics Stack Exchange most recent 30 from physics.stackexchange.com 2019-06-17T16:49:22Z https://physics.stackexchange.com/feeds/question/90437 http://www.creativecommons.org/licenses/by-sa/3.0/rdf https://physics.stackexchange.com/q/90437 3 Does there exist electric field around all the substances? Immortal Player https://physics.stackexchange.com/users/29762 2013-12-16T21:25:43Z 2013-12-16T21:51:35Z <blockquote> <ul> <li>A system of two equal and opposite charges separated by a certain distance is called an electric dipole. </li> <li>Electric dipole moment ($p$) is defined as the product of either charge ($q$) and the length ($2a$)of the electric dipole. </li> <li>Magnitude of electric field ($E$) due to an electric dipole at a distance $r$ from its centre in a direction making an angle $\theta$ with the dipole is given by the equation,$$E=\frac{1}{4\pi\epsilon}.\frac{p\sqrt{3\cos^2\theta+1}}{r^3}$$<br> where, $p=2aq$ ($2a$ is the distance of separation of the charges $q$). </li> </ul> </blockquote> <p>From the above equation, I thought that, electric field around a neutral body won't be zero. Electric field around a neutral body would be zero if and only if the distance of separation between the dipole charges is zero (from the equation, we can notice that $E$ tends to zero as $p$ tends to zero or $2a$ tends to zero). So, even if a body is neutral, I thought that electric field need not be zero. </p> <p>I got a doubt here. We know that, in a neutral atom, electron and proton have equal and opposite charges, and even they are separated by a certain distance. So, I assumed a pair of electron and proton to behave as a dipole, so that I could fit them to the above dipole equation. I thought, as the distance between electron and proton is not zero, there must exist electric field around them. As a result, we can expect electric field around all the atoms, thus producing a vector added field around the substance. But, we don't feel electric field around all the substance. Is it that electric field around the substances negligible? I don't know whether I am correct or wrong, or whether I have misunderstood the concept. If any is the case, please explain. </p> <p>[My book mentions one related example: "The molecules of water, ammonia, etc behave as electric dipoles. It is because, the centres of positive and negative charges in these molecules lie at a small distance from each other" It is to be noted that, molecules are considered here and atoms are neglected.]</p> https://physics.stackexchange.com/questions/90437/-/90438#90438 1 Answer by jinawee for Does there exist electric field around all the substances? jinawee https://physics.stackexchange.com/users/21817 2013-12-16T21:37:05Z 2013-12-16T21:51:35Z <blockquote> <p>So, I assumed a pair of electron and proton to behave as a dipole</p> </blockquote> <p>Classically, this is correct. It would behave as a dipole.</p> <p>But in quantum mechanics we don't talk about a localized electron, but about orbitals. This is because particles have an associated wavefunction $\psi(t)$, which tells you the probability of finding your particle at a particular place.</p> <p>In the case of an electron and a proton (hydrogen atom), the orbital has spherical symmetry. This means that the will be no net charge.</p>