Explain why, when a polythene rod which has been rubbed with any cloth is held high above small pieces of paper on a table, the pieces of paper jump up and down repeatedly between the table and rod.
could it be the net charge on the rod is not zero? Those excess charges attract the paper pieces, as the charges in the paper (an insulator), move, twist, or however, move toward the rod, this creating an attraction with the rod. The paper pieces are being charged by "induction". Read about it here.
http://stao.ca/res2/demo/9AP-P2.pdf
The observed phenomenon is known as static electricity or electrostatics. When a polythene rod is rubbed with a cloth, it becomes charged due to a phenomenon called triboelectric charging. This means that the rubbing process transfers electrons between the two materials, causing an imbalance in the charges.
As a result, the polythene rod becomes negatively charged, as it gains extra electrons from the cloth. Meanwhile, the cloth becomes positively charged due to losing some of its electrons to the rod. This charge difference between the rod and the pieces of paper on the table is what causes the jumping effect.
When the negatively charged rod is held above the table, it creates an electric field around it. The electric field induces a separation of charge in the pieces of paper. The electrons in the paper are repelled by the negatively charged rod, causing them to move away from the rod and towards the table.
However, the presence of the positively charged cloth on the rod attracts the electrons in the paper towards the rod. This push and pull effect creates an oscillation of the electrons in the paper, causing the pieces of paper to jump up and down repeatedly between the table and rod.
This behavior is because the charges in the pieces of paper are not free to move entirely. They are constrained within the paper, and therefore cannot neutralize the charges on the rod fully. This leads to a continuous attraction and repulsion between the rod and the paper, resulting in the observed jumping effect.
It is important to note that the actual behavior of the pieces of paper depends on several factors, including the size and shape of the paper, the distance between the rod and the paper, and the surrounding environment's humidity level.
When a polythene rod is rubbed with any cloth, it becomes charged with static electricity. This phenomenon occurs due to the transfer of electrons from the cloth to the rod. The electrons move from the cloth, which has an excess of electrons, to the rod, which has a deficit of electrons.
Now, when the charged polythene rod is held high above small pieces of paper on a table, something called electrostatic induction takes place. The charged rod creates an electric field around it.
The electric field exerts a force on the tiny electrons in the pieces of paper, causing them to move within the paper. As a result, the pieces of paper become polarized, with one side being attracted to the rod, and the other side being repelled from the rod.
This attraction and repulsion between the rod and the paper cause the pieces of paper to jump up and down repeatedly. The electrons in the paper are drawn towards the charged rod, making one side of the paper more negatively charged and the other side more positively charged.
This polarization creates an imbalance of charges, resulting in an overall attractive force between the negatively charged side of the paper and the positively charged rod. The paper jumps towards the rod due to this attractive force.
However, as the paper moves closer to the rod, the electrons in the paper repel the excess electrons on the rod, creating a repulsive force. This force causes the paper to move away from the rod again.
This process repeats as long as the rod remains charged, causing the pieces of paper to continuously jump up and down between the table and the rod.
So, in summary, the jumping of the small pieces of paper is a result of the attractive and repulsive forces between the charged polythene rod and the polarized charges in the paper, which is caused by electrostatic induction.
Well, I guess it's curtains for those pieces of paper! When the polythene rod is rubbed with a cloth, it becomes like a teenage pop star – positively charged. Meanwhile, those innocent pieces of paper are just hanging out, minding their own business, being neither positively nor negatively charged.
But when the charged rod is held above the paper pieces, a bit of comedy ensues. You see, positive charges are attracted to negative charges, like magnets on a bad blind date. So, the positive charges in the paper scraps start feeling the pull of the rod's positive charge, causing them to jump up towards it.
However, as soon as the paper gets close to the rod, they realize that they are like two positive ends of a battery – they just can't stand each other! So, the paper pieces quickly jump back down towards the table, breaking up their ill-fated attraction.
This back-and-forth dance continues as long as the rod is held above the paper. Trust me, those paper pieces might be small, but they sure know how to show off their moves on the dance floor!