This question tests conservation of electric charge and charging. When a charged rod touches a neutral conductor, electrons transfer between them until they reach the same electric potential, a process called charging by conduction. Since the rod has charge -Q (excess electrons) and touches the neutral sphere, electrons flow from the rod to the sphere, giving the sphere a negative charge. The total charge of the system (rod + sphere) remains constant at -Q, though it redistributes between the two objects. Choice C incorrectly assumes neutral objects contain no charges, when actually they have equal amounts of positive and negative charge. When solving charging problems, remember that charge transfers by contact involve actual movement of electrons, and the total charge is always conserved.

This question tests conservation of electric charge and charging. When the negative rod approaches sphere 1, it repels electrons through the contact point into sphere 2, making sphere 1 positive (electron deficit) and sphere 2 negative (electron excess). Separating the spheres while the rod is still nearby locks in this charge separation - sphere 1 remains positive and sphere 2 remains negative even after the rod is removed. The total charge of both spheres together remains zero, conserving charge. Choice B incorrectly suggests the rod can transfer electrons without contact, but the charge separation occurs through electron movement between the touching spheres. To solve multi-object induction problems, track electron flow between connected conductors before they separate.

This question tests conservation of electric charge and charging. When a charged rod approaches a conductor, it causes polarization - electrons redistribute within the conductor but none enter or leave, so the net charge remains zero. When the rod is removed, the polarized charges redistribute back to uniform distribution, and the conductor returns to its original neutral state with zero net charge. No charge transfers between rod and conductor without contact or grounding. Choice B incorrectly claims polarization creates net charge, but it only rearranges existing charges. Remember that polarization is temporary charge separation that requires no charge transfer - removing the external influence returns the conductor to neutral.

This question tests conservation of electric charge and charging. When conductors with different charges touch, electrons flow between them until they reach the same electric potential, redistributing the total charge. The initial total charge is 0 + (-Q) = -Q, and by conservation of charge, the final total must also be -Q, now shared between both spheres. Neither sphere remains at its initial charge - the neutral sphere becomes negative and the charged sphere becomes less negative. Choice B incorrectly suggests opposite charges cancel and vanish, but charge cannot be destroyed, only redistributed. When analyzing charge sharing, always apply conservation: the sum of all charges before contact equals the sum after contact.

This question tests conservation of electric charge and charging. In charging by induction, a charged object influences charge distribution in a conductor without touching it - the negative rod repels electrons in the sphere to the far side, leaving the near side positive. When the sphere is grounded while the rod is nearby, electrons flow from the sphere through the ground wire to escape the repulsion, leaving the sphere with a net positive charge. After removing the ground and then the rod, this positive charge redistributes uniformly on the sphere. Choice C incorrectly suggests electrons can jump through air from rod to sphere, but charge transfer requires contact or a conducting path. To analyze induction problems, track electron movement step-by-step and remember that grounding provides a path for charge to flow.

This question tests conservation of electric charge and charging. When a charged rod is brought near a neutral conductor without touching or grounding, it only causes temporary charge separation (polarization) within the conductor—electrons move to one side, leaving positive charge on the other. However, the total number of electrons and protons in the sphere remains unchanged, so the net charge stays zero. When the rod is removed, the separated charges recombine, returning the sphere to its original neutral state with zero net charge. Choice A incorrectly suggests electrons can jump through air—at typical voltages, air is an insulator preventing charge transfer without contact. For polarization without grounding: charge separates temporarily but net charge always remains unchanged.

This question tests conservation of electric charge and charging. When glass is rubbed with silk, friction provides energy to overcome the binding forces holding electrons to atoms, allowing electron transfer between the materials. Glass has a weaker hold on its outer electrons compared to silk, so electrons transfer from glass to silk during rubbing, leaving the glass with a deficit of electrons (positive charge) and the silk with excess electrons (negative charge). The total charge of the glass-silk system remains zero, conserving charge. Choice B incorrectly suggests protons move—protons are bound in atomic nuclei and cannot transfer during rubbing; only electrons are mobile. In triboelectric charging, remember: only electrons transfer, and the material losing electrons becomes positive.

This question tests conservation of electric charge and charging. When a positively charged glass rod touches a conductor, charge transfer occurs through electron movement - the rod's positive charge means it has a deficit of electrons. Electrons from the neutral electroscope are attracted to and transfer onto the positive rod, leaving the electroscope with fewer electrons and thus a net positive charge. After the rod is removed, the electroscope retains this positive charge. Choice B incorrectly suggests protons transfer, but protons are bound in atomic nuclei and don't move during electrostatic charging - only electrons transfer. When analyzing contact charging, remember that positive charge means electron deficit, and electrons always move from where they're more concentrated to where they're less concentrated.

This question tests conservation of electric charge and charging. Charge conservation is a fundamental principle stating that the total charge in an isolated system remains constant - charge cannot be created or destroyed. When the negatively charged sphere touches the neutral sphere, electrons redistribute between them, but the total number of electrons (and thus total charge) in the two-sphere system remains exactly the same as initially. The charge simply redistributes from one sphere to both spheres. Choice D incorrectly suggests charge can be destroyed as heat, confusing charge with energy - while energy can convert to heat, charge itself is always conserved. To solve any charging problem, apply charge conservation: count total charge before and after any process.

This question tests conservation of electric charge and charging. When two identical conducting spheres touch, charge redistributes between them until they reach the same electric potential, which for identical spheres means equal charge. The total initial charge is (+4 μC) + (-2 μC) = +2 μC, and this total must be conserved throughout the process. Since the spheres are identical, this +2 μC divides equally, giving each sphere +1 μC after separation. Choice C incorrectly assumes opposite charges "cancel and vanish"—charge is conserved, not destroyed; the charges redistribute but the total remains +2 μC. When identical conductors touch, always calculate total charge first, then divide equally between them.