Charging Porcelain Insulators?

📌 CONCEPT: When a glass rod is rubbed with silk cloth, it becomes positively charged due to the transfer of electrons from the silk to the glass rod. This positively charged glass rod can then induce charges in the nearby identical porcelain insulators without actually touching them.

📐 RULE / FORMULA: The principle that applies here is Coulomb's Law and the concept of electric induction, which states that a charged object can induce polarization in a nearby neutral object. The induced polarization results in the redistribution of charges within the neutral object, causing it to become oppositely charged.

💡 WORKED EXAMPLE: Let's assume that the positively charged glass rod is brought close to three identical porcelain insulators. Due to electric induction, the insulators will become oppositely charged, with two of them becoming negatively charged and one becoming positively charged. This is because the electrons in the insulators are repelled by the positively charged glass rod, causing them to move to the opposite side of the insulator. The negatively charged insulators will be on the side of the glass rod, while the positively charged insulator will be on the opposite side.

⚠️ COMMON MISTAKE: Students often mistakenly assume that all the insulators will become uniformly charged, when in fact, only two will be negatively charged and one will be positively charged due to the redistribution of charges through electric induction.