Suppose a rod is given a negative charge by rubbing it with wool. Whic

Suppose a rod is given a negative charge by rubbing it with wool. Which one of the following statements is correct in this case ?

[amp_mcq option1=”The positive charges are transferred from rod to wool” option2=”The positive charges are transferred from wool to rod” option3=”The negative charges are transferred from rod to wool” option4=”The negative charges are transferred from wool to rod” correct=”option4″]

This question was previously asked in

UPSC NDA-1 – 2017

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The question describes a rod being given a negative charge by rubbing it with wool and asks about the charge transfer process.

When two different materials are rubbed together, electrons can be transferred from one material to the other due to differences in their electron affinities. This process is called charging by friction or triboelectric effect. If the rod gains a negative charge, it means it has received negative charge carriers, which are electrons. Since positive charges (protons) are fixed within the nucleus of atoms in the solid material, they are generally not transferred during rubbing. Therefore, the negative charge acquired by the rod must come from the wool.
– If the rod becomes negatively charged, it has *gained* electrons.
– These electrons must have come from the wool.
So, negative charges (electrons) are transferred from the wool to the rod. The wool loses electrons and becomes positively charged.

The triboelectric series lists materials in order of their tendency to gain or lose electrons when rubbed. Materials higher on the list tend to lose electrons and become positively charged, while materials lower on the list tend to gain electrons and become negatively charged. Wool is typically higher than many common materials like plastic or ebonite (used for rods), indicating it tends to lose electrons to these materials when rubbed.

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