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NEETS Module 1 — Chapter 1

Matter, Energy, and Electricity  ·  NAVEDTRA 14173

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Chapter 1: Matter, Energy & Electricity

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

📚 Source: NEETS Module 1
⏱ Est. Time: 60–75 minutes
🎯 Pass Score: 80%
📝 Final Questions: 20

🎓 LEARNING OBJECTIVES

1

Matter, Atoms & Atomic Structure

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

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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. Over 100 are known. 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 ≈ 1/1837 of proton
  • 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 holds a maximum of 2n² electrons (n = shell number). 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 lights and TV picture tubes.

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.

🧪 Section 1 Knowledge Check

1. What is the maximum number of electrons in the M shell (n=3)?

2. An atom that has gained extra electrons becomes a:

✅ Section 1 Complete!
2

Conductors, Semiconductors & Insulators

All materials can be classified based on their ability to conduct electric current. This is determined primarily by the number of valence electrons.

⚡
Conductors

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

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 — Used where oxidation/corrosion resistance is critical
  • 4. Aluminum — Used for high-tension power lines where weight matters

In a copper conductor at room temperature, heat energy frees many electrons. Without an external force, these free electrons move randomly. An external force causes them to move directionally — this controlled flow is called an electric current.

🧪 Section 2 Knowledge Check

1. A material with 4 valence electrons is classified as a:

2. Which conductor is MOST commonly used because of its cost-to-conductivity ratio?

✅ Section 2 Complete!
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. Field strength diminishes with the square of the distance from the source. Lines of force leave positive charges and enter negative charges.

🧪 Section 3 Knowledge Check

1. According to Coulomb's Law, if the distance between two charged bodies is doubled, the force between them:

2. Electrostatic lines of force leaving a positive charge travel:

✅ Section 3 Complete!
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.

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Magnetic Materials

Attracted by magnets — iron, steel, nickel, cobalt

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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; largely obsolete
  • Artificial/Permanent — High reluctance; retain magnetism; hardened steel alloys
  • Artificial/Temporary — Low reluctance; lose magnetism quickly; 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 distributes through a material. Inverse of reluctance.

🧲 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 (from N pole, through external space, to S pole, then through the magnet)
  • They never cross each other
  • They pass through ALL materials (magnetic and nonmagnetic)
  • 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 soft-iron shield (magnetic screen) is used to redirect flux around the instrument.

🧪 Section 4 Knowledge Check

1. A material with LOW reluctance should be used to make a:

2. The Domain Theory of magnetism is based on:

✅ Section 4 Complete!
5

Electrical Energy & Voltage

Energy is defined as the ability to do work. Work is the product of force and displacement.

🏃
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 = 6.28 × 10¹⁸ electrons. Named after Charles Coulomb.

Electromotive Force (EMF) / Voltage

One unit of electrical potential energy exists between two bodies when a charge of 1 coulomb exists between them. Measured in VOLTS (V).

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: electron flow is directly proportional to applied voltage. Increase voltage → increase flow; decrease voltage → decrease flow.

🧪 Section 5 Knowledge Check

1. How many electrons make up one coulomb of charge?

2. Convert 0.000025 volts to microvolts (µV):

✅ Section 5 Complete!
6

Six Methods of Producing Voltage

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

1
FRICTION

Voltage produced by rubbing certain materials together. Creates static charges but not practically maintainable. Van de Graaff generator uses this principle to produce millions of volts for nuclear research.

2
PRESSURE (Piezoelectricity)

Squeezing or stretching crystals (quartz, Rochelle salts, tourmaline) produces opposite charges on their surfaces. Used in microphones, phonograph cartridges, sonar, and radio oscillators.

3
HEAT (Thermoelectricity)

Heating the junction of two dissimilar metals (a thermocouple) produces voltage. Copper electrons move away from heat; iron electrons move toward heat. Used in temperature measurement and control equipment.

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LIGHT (Photoelectricity)

Light striking photosensitive materials (silver oxide, copper oxide) dislodges electrons, creating a photoelectric voltage. Used in television cameras, automatic manufacturing, door openers, and burglar alarms.

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CHEMICAL ACTION

Two dissimilar metals (electrodes) in an electrolyte solution create a difference of potential — a primary cell. Wet cells use liquid electrolyte (auto battery); dry cells use paste electrolyte (flashlights). Multiple cells = battery.

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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 the basis of ALL generators.

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

1. Which method of producing voltage is the basis of ALL generators?

2. Piezoelectric crystals are commonly used in which devices?

✅ Section 6 Complete!

📋 Final Assessment

Answer all 20 questions, then click Submit. A score of 80% (16/20) or higher is required to pass.

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 types of electrical charge?

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

10. 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 induced EMF when the motion of a conductor in a magnetic field is reversed?

20. Which of these is NOT one of the six recognized methods of producing voltage?

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NEETS Module 1 — Chapter 1
Matter, Energy & Electricity
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