【People's Education Press】High School Physics: Compulsory Course III: Exploring the Microscopic World – The Origin of Electric Charge and the Microscopic Nature of Charged Objects

Beneath the solid facade of all things lies a ceaseless world of electricity. The essence of electrification is not the creation of charge from nothing, but rather the disruption of internal microscopic particle balance.the disruption of microscopic particle equilibrium.

1. Microscopic Carriers of Electric Charge

Atoms consist of positively charged nuclei and negatively charged electrons. In metallic conductors, some outer-shell electrons break free from their atoms and become mobile 'free electrons' that move through the internal 'sea' of the metal.free electrons, while atoms that have lost electrons become fixed at lattice nodes asions.

2. Physical Mechanisms of Charging

Frictional Charging: Different materials have varying abilities to bind electrons. During friction, electrons transfer from the material with weaker electron binding to the one with stronger binding, causing both objects to acquire equal but opposite charges.
Inductive Charging: Usingelectrostatic induction(Electrostatic induction), which causes free charges within a conductor to redistribute under an external electric field. The end near the charged object develops an opposite charge, while the far end develops a like charge.

3. Measuring Electric Charge

We useelectric charge (Electric quantity) to describe the amount of charge on an object, whose SI unit iscoulomb (C). By usingan electroscope (Electroscope), we can qualitatively assess the strength of an object's charge by observing the angle of its leaves. Remember, electric charges follow the eternal rule: like charges repel, unlike charges attract.

QUESTION 1

Which of the following statements about electric field strength is correct?

The electric field strength $E$ is determined solely by the electric field itself and is independent of the test charge $q$ placed within it.

The electric field strength $E$ is directly proportional to the electric force $F$ experienced by the test charge $q$.

If no test charge is placed at a point in the electric field, then the electric field strength at that point is zero.

The direction of the electric field strength is always the same as the direction of the electric force.

QUESTION 2

In dry weather, people often receive a shock when removing their outerwear and touching a metal doorknob. What physical phenomenon does this represent?

Inductive Charging

Contact charging

Static discharge caused by frictional charging

Charge being created from nothing

QUESTION 3

As shown in the figure, a positively charged conductor sphere $C$ is brought near an uncharged horseshoe-shaped conductor. If the conductor is split into two parts, A and B, along its midline, what is the relationship between their charges?

$Q_A = Q_B$

$Q_A = -Q_B$

$Q_A > Q_B$

$Q_A < Q_B$

QUESTION 4

Which statement about the elementary charge is correct?

The elementary charge refers to the electron or proton itself

All charged bodies have charges that are integer multiples of the elementary charge $e$

The value of the elementary charge is typically taken as $1.60 \times 10^{-23} \text{ C}$

The elementary charge can be divided through frictional charging

QUESTION 5

The leaves of the electroscope open because:

The leaves are affected by gravitational force

Like charges repel each other

Unlike charges attract each other

Airflow pushes the leaves apart