N1

NEETS Module 1 — Chapter 1

Matter, Energy, and Electricity  ·  NAVEDTRA 14173

0 of 6 Sections Complete
1
2
3
4
5
6

Chapter 1: Matter, Energy & Electricity

Foundational concepts in atomic structure, electrostatics, magnetism, and voltage production — the building blocks of all electricity and electronics.

Course Duration: 50–65 minutes

📚 Source: NEETS Module 1 (NAVEDTRA 14173)
🎯 Pass Score: 80% (16 of 20)
📝 Final Questions: 20

🎓 LEARNING OBJECTIVES

  • Define matter, element, compound, mixture, molecule, atom, electron, proton, neutron, and ion
  • Explain photons, energy levels, and shells/subshells
  • Distinguish conductors, semiconductors, and insulators by valence
  • Describe static electricity, Coulomb’s Law, and electrostatic fields
  • Explain magnetism, magnetic poles, theories of magnetism, and magnetic shielding
  • Define energy, the coulomb, and the volt
  • Identify the six methods of producing voltage and where each is used

🛈 HOW THIS COURSE WORKS

  • Six sections, each ending with a knowledge check. You get two attempts, and a first miss gives you a hint rather than the answer. Answering unlocks the next section.
  • Then a 20-question final assessment, different from the knowledge checks.
  • When you submit, your results are emailed automatically to the training administrator and to you, whether or not you pass.
1

Matter, Atoms & Atomic Structure

Matter is anything that occupies space and has weight. It exists in three states: solid, liquid, and gaseous.

🧱
Solid

Fixed shape and volume

💧
Liquid

Fixed volume, variable shape

💨
Gaseous

Variable shape and volume

Element

A substance that cannot be reduced to a simpler substance by chemical means. 118 are now confirmed (NEETS, written in the 1990s, said “more than 100”). Examples: iron, gold, silver, copper, oxygen.

Compound

A chemical combination of two or more elements that can be separated by chemical — but not physical — means. Example: water (H₂O) = hydrogen + oxygen.

Mixture

A combination of elements/compounds, NOT chemically combined, separable by physical means. Example: air (nitrogen, oxygen, CO₂, rare gases).

Molecule

A chemical combination of two or more atoms; the smallest particle of a compound that retains its characteristics.

Molecules are made of atoms — the smallest particle of an element that retains its characteristics. Atoms of each element are unique; there are as many atom types as there are elements.

SUBATOMIC PARTICLES

  • Electron — Negative charge; orbits nucleus; mass ≈ 1/1836 of a proton (NEETS rounds the ratio to 1,837)
  • Proton — Positive charge; resides in nucleus; equal charge magnitude to electron
  • Neutron — No charge (neutral); in nucleus; mass ≈ equal to proton

In a neutral atom, protons and electrons are equal in number. The atomic number equals the number of protons. Hydrogen has 1 proton (atomic number 1); helium has 2 (atomic number 2).

ENERGY LEVELS & SHELLS

Electrons exist in specific energy levels called shells, labeled K, L, M, N, O, P, Q from the nucleus outward. Each shell can hold a maximum of 2n² electrons (n = shell number): K = 2, L = 8, M = 18, N = 32. This is the theoretical capacity — in real atoms the outer shells (O, P, Q) never fill completely. Shells divide into subshells: s (max 2e), p (max 6e), d (max 10e), f (max 14e).

An electron gains energy by absorbing a photon, jumping to a higher orbit. When it returns, it emits a photon — this principle drives fluorescent lamps (and the older CRT picture tubes NEETS mentions).

Valence

The number of electrons in an atom's outermost (valence) shell. Determines chemical and electrical properties.

Ion

An atom that has gained electrons (negative ion) or lost electrons (positive ion). Ionization requires a transfer of energy. Only electrons move in ordinary ionization — the protons in the nucleus stay put.

🧪 Section 1 Knowledge Check

Air is made up of nitrogen, oxygen, carbon dioxide, and other gases that are not chemically combined. What is air?

Attempts: 0/2
2

Conductors, Semiconductors & Insulators

All materials can be classified based on their ability to conduct electric current. NEETS uses the number of valence electrons as a general rule of thumb. (Atomic structure and temperature matter too — the counts below are typical, not absolute.)

⚡
Conductors

Normally 3 or fewer valence electrons. Free electrons flow easily. Examples: silver, copper, gold, aluminum.

🔌
Semiconductors

Usually 4 valence electrons. Between conductors and insulators. Examples: germanium, silicon.

🛑
Insulators

Normally 5 or more valence electrons. Very few free electrons. Examples: rubber, plastic, glass, wood, mica.

BEST CONDUCTORS (in order)

  • 1. Silver — Best conductor; high cost limits use
  • 2. Copper — Most widely used; good balance of cost and conductivity
  • 3. Gold — Resists oxidation and corrosion, so it’s used to plate connector and relay contacts
  • 4. Aluminum — Light and inexpensive, so it’s used for overhead high-voltage transmission lines

In a copper conductor at room temperature, heat energy frees many electrons. Without an external force, these free electrons move randomly. An external force (a voltage) causes them to drift in one direction — this directed flow is called an electric current.

🧪 Section 2 Knowledge Check

Gold conducts less well than silver or copper. Why is it still used to plate connector and relay contacts?

Attempts: 0/2
3

Electrostatics & Charged Bodies

Electrostatics is the study of electricity at rest. Interest dates to ancient Greece — Thales of Miletus discovered that rubbed amber attracted small objects. William Gilbert (~1600) expanded this work, classifying materials with similar properties as "electrics."

Charles Dufay (1733) discovered two opposite kinds of electricity. Benjamin Franklin introduced the terms positive and negative to describe them.

STATIC ELECTRICITY

A neutral body has equal protons and electrons. Remove electrons → body becomes positively charged. Add electrons → body becomes negatively charged. When two charged bodies cannot equalize (because they're not in contact), the force between them is static electricity — an electrostatic force.

Static charges are most easily created between non-conducting materials by friction. Rubbing a hard rubber rod with fur causes the rod to accumulate electrons (becoming negative) while the fur becomes positive.

⚡ FUNDAMENTAL LAW: LIKE CHARGES REPEL — UNLIKE CHARGES ATTRACT

Coulomb's Law of Charges

Charged bodies attract or repel with a force DIRECTLY proportional to the product of their individual charges, and INVERSELY proportional to the square of the distance between them.

Electric Field of Force

The space surrounding charged bodies where their influence is felt. Also called an electrostatic field or dielectric field. For a point charge, field strength falls off with the square of the distance from the source. Lines of force leave positive charges and enter negative charges.

🧪 Section 3 Knowledge Check

A hard rubber rod is rubbed with fur. What charge does the rod take on, and why?

Attempts: 0/2
4

Magnetism & Magnetic Fields

Magnetism is a property that enables materials to attract iron. Magnetic and electrical phenomena are inseparably linked — modern computers, motors, generators, and speakers all depend on both.

🧲
Magnetic Materials

Attracted by magnets — iron, steel, nickel, cobalt

📄
Nonmagnetic

Not attracted — paper, wood, glass, tin

⚙️
Ferromagnetic

Easily magnetized — iron, steel, cobalt, Alnico, Permalloy

TYPES OF MAGNETS

  • Natural Magnets — Magnetite (lodestone); found in nature; little practical use today
  • Artificial/Permanent — High reluctance (low permeability) and high retentivity; hardened steel and alloys such as Alnico
  • Artificial/Temporary — Low reluctance (high permeability); lose most magnetism when the magnetizing force is removed; soft iron, silicon steel
Reluctance

Opposition a material offers to magnetic lines of force. High reluctance → permanent magnet. Low reluctance → temporary magnet.

Retentivity

A material's ability to retain residual magnetism after the magnetizing force is removed.

Permeability

The ease with which magnetic flux passes through a material. High permeability goes with low reluctance, and the reverse. (Strictly, reluctance also depends on the part’s length and cross-section.)

🧲 LAW OF MAGNETIC POLES: LIKE POLES REPEL — UNLIKE POLES ATTRACT

THEORIES OF MAGNETISM

  • Weber's Molecular Theory — Each molecule is a tiny magnet. Magnetization aligns these molecular magnets; demagnetization randomizes them.
  • Domain Theory (modern) — Groups of atoms (domains) align their electron spins. In an unmagnetized material, domains point randomly. Magnetizing aligns domains in one direction.

PROPERTIES OF MAGNETIC LINES OF FORCE

  • They form closed loops (outside the magnet from N pole to S pole, then back from S to N inside the magnet)
  • They never cross each other
  • They pass through all materials (magnetic and nonmagnetic) — nothing blocks them
  • Enter/leave magnetic material at right angles to the surface

Magnetic shielding: There is no known insulator for magnetic flux. To protect sensitive instruments, a shield of high-permeability material (soft iron, or a nickel-iron alloy such as mu-metal) surrounds the instrument. The flux takes the easier path through the shield and is directed around the instrument rather than through it.

🧪 Section 4 Knowledge Check

How is a sensitive instrument protected from a nearby magnetic field?

Attempts: 0/2
5

Electrical Energy & Voltage

Energy is defined as the ability to do work. Work is the product of force and the distance moved in the direction of the force.

🏃
Kinetic Energy

Energy of motion — a rolling stone, a swinging hammer

🏔️
Potential Energy

Energy of position — a suspended hammer, a coiled spring

Coulomb (Unit of Charge)

The practical unit for measuring electrical charge. 1 coulomb ≈ 6.24 × 10¹⁸ electrons. (NEETS gives 6.28 × 10¹⁸, an older value. Since 2019 the SI defines the electron charge as exactly 1.602176634 × 10⁻¹⁹ C, which works out to about 6.24 × 10¹⁸.) Named after Charles-Augustin de Coulomb.

Electromotive Force (EMF) / Voltage

The difference of potential between two charged bodies. It is measured in VOLTS (V). One volt exists between two points when it takes 1 joule of energy to move 1 coulomb of charge between them (1 V = 1 J/C). Volts and coulombs are different units: a charge is not a voltage.

VOLTAGE UNITS

  • kV (kilovolt) = 1,000 V — e.g., 20,000 V = 20 kV
  • mV (millivolt) = 0.001 V — e.g., 0.001 V = 1 mV
  • µV (microvolt) = 0.000001 V — e.g., 0.000025 V = 25 µV

A fundamental law: for a given resistance, electron flow is directly proportional to applied voltage. Increase voltage → increase flow; decrease voltage → decrease flow. (This is Ohm’s law, covered in Chapter 3.)

🧪 Section 5 Knowledge Check

A sensor's output is 0.000025 V. How is that written with a metric prefix?

Attempts: 0/2
6

Methods of Producing Voltage

A voltage source is a device that supplies and maintains voltage while electrical apparatus is connected to its terminals. NEETS describes six methods for producing electromotive force (EMF):

1
FRICTION

Voltage produced by rubbing certain materials together. The first method discovered. It creates static charges, but not a practical, steady supply of power. The Van de Graaff generator uses this principle (a moving belt) to build potentials of millions of volts for nuclear research.

2
PRESSURE (Piezoelectricity)

Squeezing or stretching crystals (quartz, Rochelle salts, tourmaline) produces opposite charges on their surfaces. Widely used in sound and communications systems where small signal voltages are useful — crystal microphones, sonar transducers, and quartz crystals that control radio and clock frequencies. Gas-grill and lighter igniters use it to make a spark.

3
HEAT (Thermoelectricity)

Heating the junction of two dissimilar metals (a thermocouple) produces voltage. NEETS’s model: in most metals, such as copper, electrons move away from the hot end; in iron they move toward it, so a copper–iron junction develops a voltage. The output depends on the temperature difference between the hot (measuring) junction and the cold (reference) junction — this is the Seebeck effect, and the output is only millivolts. Used to measure temperature and as heat sensors in automatic temperature control equipment (for example, furnace flame sensing).

4
LIGHT (Photoelectricity)

Light striking photosensitive materials dislodges electrons, creating a photoelectric voltage. NEETS lists silver oxide and copper oxide; today’s solar (photovoltaic) cells and light sensors use silicon. Used in light sensors, automatic manufacturing controls, door openers, burglar alarms, and solar panels.

5
CHEMICAL ACTION

Two dissimilar metals (electrodes) in an electrolyte create a difference of potential — a cell. Wet cells use a liquid electrolyte; dry cells use a paste. Primary cells can’t be recharged (alkaline flashlight cells); secondary cells can (the lead-acid auto battery). Several cells connected together form a battery.

6
MAGNETISM (Electromagnetic Induction)

Moving a conductor through a magnetic field (or the field through a conductor) produces voltage. Requires: a conductor, a magnetic field, and relative motion. Reversal of motion reverses polarity. This is how the generators in power plants produce nearly all commercial electric power.

THREE CONDITIONS FOR VOLTAGE BY MAGNETISM

  • A conductor in which voltage will be produced
  • A magnetic field in the conductor's vicinity
  • Relative motion between field and conductor — conductor must cut lines of force

🧪 Section 6 Knowledge Check

An automatic door opener uses a beam of light striking a sensitive cell. Which method of producing voltage does it rely on?

Attempts: 0/2

📋 Final Assessment

Answer all 20 questions, then submit. A score of 80% (16/20) or higher is required to pass. These questions are different from the section knowledge checks.

1. Matter is defined as anything that:

2. Which statement best describes an ELEMENT?

3. The smallest particle of an element that retains that element's characteristics is a(n):

4. Which subatomic particle has NO electrical charge?

5. The maximum number of electrons in the K shell (n = 1) is:

6. Conductors typically have how many valence electrons?

7. Which material is the BEST electrical conductor?

8. Benjamin Franklin used which terms to describe the two kinds of electrical charge?

9. According to Coulomb's Law, the force between two charged bodies is:

10. According to NEETS, a material with HIGH reluctance is best used to make a:

11. The ability of a material to retain residual magnetism after the magnetizing force is removed is called:

12. Which statement about magnetic lines of force is TRUE?

13. The Domain Theory of magnetism attributes magnetization to:

14. Energy is defined as:

15. One coulomb equals the charge of approximately how many electrons?

16. Voltage produced by squeezing a quartz crystal is an example of:

17. A thermocouple produces voltage by:

18. For voltage to be produced by magnetism, which THREE conditions must exist?

19. What happens to the direction of the induced EMF when the motion of a conductor in a magnetic field is reversed?

20. Which of these is NOT one of the six methods of producing voltage described in NEETS?

Assessment Results

0%

Score: 0 / 0

Percentage: 0%

Status: —

Time in course: —