HCV2 Obj2 Pg 120 Q5

Why does a phonograph record attract dust particles just after it is cleaned?

hi shohini, thanks for joining the forum. Coming to question when will a particle will attract another particle when there is some of sort of interaction (forces) between them. Dust contains huge no of particles, which again is made of number of atoms, which contain electrons. Therefore now the question boils down to finding the sort of interaction mentioned above. Since we already now that the gravitational force is the weakest force at short distances. We rule out it. the only other force is of electrostatic in nature. Now does this electrostatic force comes into play in the question. Since rubbing any two objects creates friction between the two objects and causes the electrons to rip (only some) from their positions bound to the atoms. Now these electrons are transferred to other object. Therefore making it electrically charged. Now there suppose we assume that the phonograph is made up of plastic, so rubbing it with a cloth makes it electrically charged. the sign of the charge is not to be bothered. Since any charged body attracts any neutral body ( by polarisaton). Now the phonograph is electrically charged, the dust particles are uncharged. Now the charged both causes polarization in the dust particles and the end (the dust as a whole is uncharged, only separation of charges takes place) nearest to the phonograph becomes oppositely charged with of phonograph. We know that oppositely charged objects attract each other. So now the dust particles get attracted to the phonograph.

I really sorry for making it too long. But I have assumed that u are new to electricity & magnetism. So wanted to give a clearer picture.

Hope this helps
Pinnaka

Hey thank you for ur explanation. It really helped. Hope u'll bear with me when I send in more of my doubts.

u are always welcome