Conductors and Insulators

The governing concept is electrostatic induction in a conductor. A nearby charged body produces an electric field, and this field exerts a force on the mobile conduction electrons. The electrons redistribute themselves until electrostatic equilibrium is reached, although the body has not touched the conductor. Protons remain bound in atomic nuclei, and charge is not destroyed or newly created. Therefore option A is correct; the other choices contradict charge mobility and conservation.

The relevant principle is charge separation by electrostatic induction. Electrons in a neutral conductor are mobile, so the positively charged rod attracts them toward the nearer end. That end gains an excess of electrons and becomes negatively charged, while the farther end becomes relatively positive. The conductor as a whole still has zero net charge because no contact or charge transfer has occurred. Hence option A is correct; option B reverses the electron movement.

Electrostatic induction explains the result. A negatively charged rod repels the mobile electrons inside the neutral conductor, pushing them toward the far side. The near side is therefore left with an electron deficiency, so it behaves as positively charged. The conductor’s total charge remains zero because the rod has not touched it; only the distribution has changed. Thus option A is correct. Option B incorrectly places the repelled electrons near the rod.

This is charging by induction with earthing. The positive rod attracts electrons toward the conductor’s near side. Because the conductor is connected to the Earth, which acts as a very large reservoir of mobile charge, additional electrons can flow from Earth into the conductor. After the connection is removed in the proper sequence, the conductor can retain a negative charge. Protons and neutrons do not travel through the wire, so option A is correct.

The governing concept is earthing during electrostatic induction. A negatively charged rod repels the conductor’s mobile electrons. When the conductor is connected to Earth, those repelled electrons have a path to leave the conductor and enter the Earth, which can accept a very large amount of charge. The conductor is consequently left electron-deficient and may become positively charged after disconnection. Hence option A is correct; positive ions and neutrons do not flow in the wire.

Earth behaves as a very large conducting reservoir with enormous capacity to accept or supply electrons while its potential changes negligibly. When an electron-rich conductor is connected to Earth, the excess electrons can flow through the connecting path into the Earth until electrostatic equilibrium is reached. They do not become protons or neutrons. Therefore option B is correct and illustrates earthing of conductors.

The governing concept is electrostatic induction in a conductor. A nearby charged rod produces an electric field that pushes mobile electrons toward or away from the nearer surface, while the positive and negative regions separate. No physical contact is required, and the conductor’s total charge remains unchanged. Therefore option B, induction, is correct. Charging by friction requires rubbing, discharge involves charge flow, and boiling is unrelated.

The governing concept is electrostatic induction in a conductor. A positive rod attracts the conductor’s mobile electrons, so electrons shift toward the nearby end while the opposite end becomes electron-deficient. The conductor as a whole remains neutral because no charge has entered or left. Thus the near end shows a negative effect, making option A correct. Option B reverses the direction of electron movement, option C ignores charge separation, and option D is not an electrostatic effect.

This is an application of electrostatic induction. A negative rod repels the mobile electrons inside a nearby conductor. Electrons move toward the far side, leaving the near side deficient in electrons and therefore positively charged by induction. No charge is created; the total conductor charge remains zero if it is not earthed. Hence option A is correct. Option B gives the wrong direction, while C and D ignore the nonuniform redistribution of charge.

A nearby positive rod causes electrostatic induction: mobile electrons in the conductor shift toward the rod, while the opposite side becomes electron-deficient. This produces separated induced charges, but the rod does not touch the conductor, so no charge is transferred into or out of it. The positive and negative induced amounts remain equal, giving net charge zero. Therefore option C is correct; the conductor is polarised, not charged overall.

This is charging by induction with earthing. The nearby positive rod attracts electrons toward the conductor. While the conductor is connected to Earth, additional electrons flow from Earth into it because of this attraction. If the Earth connection is removed first and the rod is then taken away, the extra electrons remain on the conductor, giving it a net negative charge. Thus option B is correct; the rod itself never transfers charge by contact.

A negative rod repels the conductor’s mobile electrons. When the conductor is earthed, some of these electrons flow into the Earth because the rod repels them. The conductor is then left with an electron deficiency. If the Earth connection is removed before the rod is taken away, that deficiency remains, so the conductor has a net positive charge. Therefore option A is correct; the amount is not necessarily double.

The governing concept is electrostatic induction in a conductor. When an external charged body is brought near a neutral conductor, its mobile electrons redistribute: one region gains electrons and becomes negatively charged, while another loses electrons and becomes positively charged. No charge is created or destroyed, so the algebraic total remains zero. Therefore option A is correct; options B and C violate charge conservation, and neutrons do not move freely through an ordinary conductor.

Earthing provides a conducting path between the charged conductor and the enormous Earth, which can accept or supply electrons with negligible change in its own potential. If the conductor is negatively charged, excess electrons can flow into Earth; if it is positively charged, electrons can flow from Earth into it. The charge is transferred, not destroyed. Therefore A is correct, while the other choices incorrectly invoke proton creation, disappearance of charge, or neutron motion.

This is charging by induction, involving a conductor and earthing. The positive rod attracts electrons within the conductor. While the rod is nearby, electrons flow from Earth into the conductor. Disconnecting Earth first traps these extra electrons; after the rod is removed, the electrons spread over the conductor. Therefore the conductor retains a net negative charge. Option B is correct; removing the rod before disconnecting Earth would instead leave no net charge.

This is charging by induction. The nearby positive rod attracts electrons toward the conductor’s near side. While the rod remains present, earthing provides a path for additional electrons to enter from Earth. Removing the earth connection first traps this excess negative charge; removing the rod afterward only redistributes it. Thus the conductor remains negatively charged, so option A is correct.

In induction, the negative rod repels the conductor’s free electrons. When the conductor is earthed while the rod remains nearby, some electrons flow from the conductor into Earth. The earth connection must be removed before taking away the rod; this leaves an electron deficiency on the conductor. After the rod is removed, that deficiency spreads over the conductor, so its final charge is positive. Option A is correct.

A charged rod maintains the separation of charges in the nearby conductor. If the rod is removed while the conductor is still connected to Earth, the external influence disappears and electrons can flow between the conductor and Earth until the conductor becomes neutral. The charge is not destroyed, and neither protons nor the elementary charge changes. Therefore option A correctly explains the failure.

A conductor contains mobile electrons. The positive rod attracts these electrons toward the nearer end, so that end develops an induced negative charge. The far end loses some electrons and therefore develops an induced positive charge. The conductor as a whole remains neutral if it is isolated; only its charge distribution changes. Thus the correct sequence is near negative and far positive, which is option A.

The governing concept is electrostatic induction in a conductor. Free electrons inside the neutral conductor are repelled by the nearby negative rod and move toward the far end. Consequently, the near end is left electron-deficient and becomes positively charged, while the far end accumulates electrons and becomes negatively charged. The conductor remains overall neutral; charges are separated, not created. Therefore option A is correct, whereas B reverses the induced signs and C and D ignore charge separation.