NEET Physics: Conductors and insulators Practice Questions

Correct answer: A — They lack free mobile charge carriers

Insulators effectively resist current because the valence electrons are strongly localized and tightly bound to their respective atomic cores, making it very difficult for them to acquire the necessary mobility to carry charge.

Correct answer: A — Conductors

Conductors possess free electrons that are able to move easily when an external potential difference is applied, allowing current flow.

Correct answer: B — Electric field

Drift velocity is determined by the force applied (Electric field) and the charge carrier mobility, which is related to the electric field strength.

Correct answer: C — Resistance to charge flow

Insulators resist charge flow due to the inability of their electrons to move freely, making them poor conductors.

Correct answer: D — Insulators

Insulators are materials that strongly resist the flow of electric current because they lack free charge carriers to move easily.

Correct answer: C — Glass

Glass is an electrical insulator because its valence electrons are tightly bound and cannot move freely to carry charge.

Correct answer: D — Higher mobility of electrons

Lower resistance implies higher conductivity. This means that for the same current density, the material with lower resistance allows the charge carriers to move more easily.

Correct answer: C — Drift Velocity Relation

The current (I) is fundamentally the product of the charge density and the velocity of the charge carriers (drift velocity, v_d) flowing across a cross-section, directly relating to the movement of charge.

Correct answer: B — Atomic structure and electron mobility

The ability of a material to conduct electricity is determined by the presence and mobility of free charge carriers (electrons). This mobility is fundamentally linked to the arrangement and energy of the valence electrons within the material's structure.

Correct answer: D — Electric Field strength

For a given current density, the drift velocity is directly proportional to the magnitude of the electric field applied, as the force driving the motion is directly related to the field strength.

Correct answer: C — Perfect conductors

Resistivity (ρ) is the reciprocal of conductivity (σ), meaning materials with higher conductivity (better conductors) have lower resistivity.

Correct answer: D — A sea of delocalized electrons

Metals are characterized by the presence of a 'sea' of highly mobile, delocalized valence electrons that are free to move throughout the crystal structure, enabling efficient charge transport.

Correct answer: B — In a conductor, electrons are free to move throughout the material, while in an insulator, they are tightly bound to their atoms.

In a conductor, the valence electrons are delocalized and form a 'sea' of free electrons, allowing easy charge transport. In an insulator, the valence electrons are tightly bound to their respective atoms and cannot move freely, thus resisting current flow.

Correct answer: C — Conductor

Conductors allow free electrons to move easily, resulting in very low resistance. Insulators offer very high resistance.

Correct answer: D — Good conductor

Resistivity is the measure of opposition to current flow. Lower resistivity implies lower resistance, meaning the material allows charge carriers to move more easily, thus classifying it as a better conductor.