Topic 3 SP025

What happens to the free electrons in a metal when an electric field is applied?

• They stop moving entirely.

• They drift slowly in the direction opposite to the field.

• They move randomly without any net direction.

• They accelerate indefinitely in the direction of the field.

What causes electric current to flow in a metal conductor?

• The movement of positive ions in the metal lattice.

• The random motion of free electrons.

• The net drift of free electrons due to an applied electric field.

• The vibration of atoms in the conductor.

How does the number of free electrons in a conductor affect the electric current?

• More free electrons result in a higher current.

• Fewer free electrons result in a higher current.

• The number of free electrons does not affect the current.

• Current flows regardless of the number of free electrons.

Which of the following is a characteristic of a good conductor?

• High resistivity

• Low resistivity

• High voltage

• Low voltage

How does the resistance of a conductor change if its length is doubled, while keeping all other factors constant?

• The resistance remains the same.

• The resistance is halved.

• The resistance is doubled.

• The resistance is quadrupled.

Two wires are made of the same material and have the same length, but Wire A has a larger cross-sectional area than Wire B. Which of the following is true about their resistances?

• Wire A has a higher resistance than Wire B.

• Wire A has a lower resistance than Wire B.

• Both wires have the same resistance.

• The resistance depends only on the material and not on the cross-sectional area.

What happens to the resistance of most metals as temperature increases?

• It decreases because electrons move faster.

• It increases because electron collisions become more frequent.

• It remains constant because resistance is not temperature-dependent.

• It fluctuates randomly with temperature.

Why does the resistivity of a metal increase with temperature?

• The number of free electrons decreases.

• The positive ions in the lattice vibrate more, increasing collisions.

• The applied voltage increases with temperature.

• The current flow stops at higher temperatures.

What does the electromotive force (emf) of a battery represent?

• The resistance within the battery.

• The current supplied by the battery.

• The energy provided per coulomb per charge.

• The voltage drop across the battery terminals.

What causes the terminal voltage of a battery to be less than its emf?

• External resistance.

• Internal resistance.

• Insufficient charge flow.

• Overcharging the battery.