1.
Copper is a good conductor of electricity because of:
Correct Answer
A. Lightly held free electrons
Explanation
Copper is a good conductor of electricity because it has lightly held free electrons. In a copper atom, the outermost electron shell is not completely filled, allowing the electrons to move freely. These free electrons can easily flow through the material when an electric field is applied, facilitating the conduction of electricity. The presence of these loosely bound electrons is what makes copper an excellent conductor.
2.
Electron flow in a circuit is always:
Correct Answer
D. From negative to positive
Explanation
Electron flow in a circuit is always from negative to positive. This is because electrons, which carry a negative charge, are attracted to the positive terminal of a power source, such as a battery. As a result, they move from the negative terminal towards the positive terminal, creating a flow of electric current. This convention of electron flow from negative to positive is used in electrical engineering and circuit analysis.
3.
The ability of free electrons to slide easily from atom to atom creates a movement called:
Correct Answer
B. Conventional flow
Explanation
Conventional flow refers to the movement of positive charges, or "holes," in a circuit, which was historically believed to be the flow of electrons. This concept was developed before the discovery of the electron's negative charge. Despite the misconception, conventional flow is still widely used in circuit analysis and is the basis for understanding the behavior of electronic devices.
4.
First used by the Greeks more than 2400 years ago we still use the word today:
Correct Answer
C. All of these
Explanation
The word "All of these" is the correct answer because it encompasses all the options given in the question. The question states that the word was first used by the Greeks more than 2400 years ago and is still used today. This implies that all the options (Electricity, Atom, and Electron) were known and used by the Greeks and are still relevant in modern times. Therefore, "All of these" is the correct answer.
5.
The metal with the highest electrical conductivity rating is:
Correct Answer
A. Silver
Explanation
Silver has the highest electrical conductivity rating among the given options. This is because silver has a high number of free electrons, which are responsible for conducting electricity. These free electrons can move easily through the metal's lattice structure, allowing for efficient flow of electric current. Gold also has high conductivity but is less conductive than silver. Steel is a poor conductor of electricity compared to silver and gold. Copper is a good conductor but has slightly lower conductivity than silver.
6.
The proton is about 1840 times heavier than the:
Correct Answer
B. Electron
Explanation
The proton is about 1840 times heavier than the electron because the proton has a mass of approximately 1 atomic mass unit (amu), while the electron has a mass of only 0.0005 amu. The proton is located in the nucleus of an atom, along with the neutron, which has a mass similar to that of a proton. However, the electron is found in the electron cloud surrounding the nucleus and is much lighter in comparison.
7.
The Greek Law of Charges states, in part that
Correct Answer
A. Unlike charges attract
Explanation
The correct answer is "Unlike charges attract." According to the Greek Law of Charges, unlike charges, which means charges with opposite signs, attract each other. This means that if one charge is positive and the other is negative, they will be attracted to each other. This is a fundamental principle in electromagnetism and explains the behavior of electric charges.
8.
The free electrons in the copper atom always carry a
Correct Answer
B. Negative charge
Explanation
In a copper atom, the outermost electron is loosely bound and can easily move from one atom to another. These free electrons are negatively charged, as electrons carry a negative charge. Therefore, the correct answer is negative charge.
9.
About 2400 years after the Greeks talked of the atom, modern scientists discovered the:
Correct Answer
D. All of these
Explanation
The statement mentions that modern scientists discovered something about 2400 years after the Greeks talked about the atom. This indicates that the discovery is related to the atom. The options given are proton, electron, neutron, and all of these. Since all of these particles (proton, electron, and neutron) are fundamental components of an atom, it can be inferred that the correct answer is "All of these."
10.
The smallest known negatively charged particle is the:
Correct Answer
D. Electron
Explanation
The correct answer is electron. The electron is a subatomic particle that carries a negative charge and is found outside the nucleus of an atom. It is considered the smallest known negatively charged particle because it has a much smaller mass compared to protons and neutrons, which are located in the nucleus. Electrons play a crucial role in chemical bonding and the behavior of atoms, making them an essential component of matter.