Basic Electricity Fundamentals

Basic Electricity Fundamentals

• Basic electricity is the study of the fundamental principles governing the flow of electric current.

Bohr's Model of the Atom

• An atom is the smallest particle of an element.
• An atom comprises protons, neutrons, and electrons.
• The number of protons identifies the element.

The Copper Atom

• Copper is a common metal used in electrical work.
• Copper atoms have 29 electrons arranged in shells around the nucleus.
• The outermost shell (valence shell) contains only one electron (valence electron).

Free Electrons

• Electrons in the outer shell of a conductor are loosely held.
• These loosely held electrons can easily break away and move between atoms.
• Once free, these electrons are called free electrons.
• The movement of free electrons constitutes electric current.

Conductors

• Conductors are materials that allow electric current to flow easily.
• Silver is the best conductor, followed by copper.
• Copper is more commonly used due to its lower cost.
• Gold is sometimes used for electrical contacts due to its malleability (ability to be shaped).

Wire Sizes (AWG)

• American Wire Gage (AWG) is a standard system for sizing electrical wires.
• The larger the AWG number, the smaller the wire's cross-sectional area.
• Larger wire sizes have lower resistance, allowing for higher current flow.

Semiconductors

• Semiconductors have four valence electrons in their valence shells.
• Adding appropriate impurities to semiconductors creates electrical properties enabling the construction of transistors and diodes.
• Silicon and germanium are common semiconductors.

Insulators

• Insulators are poor conductors of electricity.
• They have very few free electrons.
• Insulators have more than four electrons in their outer shell.
• Insulators are used to prevent current flow in unwanted areas.

Voltage

• Voltage is the electrical version of potential energy, or electrical pressure.
• One volt (V) is the potential difference between two points where one joule of energy is utilized to move one coulomb of charge between them.
• Alessandro Volta invented the voltaic pile, the first electrical battery.

Voltage Production Methods

• Methods to produce voltage include:
  • Electromagnetism (generators)
  • Light (photocells)
  • Pressure (piezoelectric)
  • Heat (thermocouples)
  • Chemical reactions (batteries)
  • Friction (static electricity)

Current Explained

• Voltage alone cannot perform work; it needs current to drive work.
• Current is the flow of charged particles (electrons) through a conductor.
• Electrical current (I) is defined as the rate of charge flow.
• I = Q/t (where I = current, Q = charge, and t = time)

Ampere: The Unit of Current

• One ampere (A) is the current flow when one coulomb of charge moves through a given cross-sectional area in one second.
• André-Marie Ampère was a pioneer in electricity.
• One coulomb of electrons is approximately 6.24 x 10¹⁸ electrons.

Resistance

• Resistance (R) is the opposition to current flow within a material.
• All materials have resistance, but conductors have very little resistance (generally insignificant).
• The exception is superconductors.
• Resistance is measured in ohms.

Ohm: The Unit of Resistance

• One Ohm (Ω) of resistance exists when one ampere of current flows through a material with one volt across it.
• George Simon Ohm is credited for the relationship between voltage, current, and resistance.

Resistors

• Resistors are circuit elements designed with specific resistance values.
• Resistors are used to control voltage and current in circuits and produce heat.
• Resistors come in fixed and variable types.

Electrical Safety

• Electricity is potentially dangerous and can cause harm without warning.
• Safety precautions should always be followed when working with electricity.

Physiological Effects of Electric Current

• Electric current's effects on the body depend on the current's magnitude.
• Currents below 1 mA generally cause no noticeable effect.
• 1 to 8 mA can cause a sensation of shock, but the individual can still let go.
• Higher currents often cause muscle contractions, loss of control, and can be lethal.

Shock Severity Factors

• Factors influencing shock severity:
  • Increased voltage - creates more severe effects.
  • Moisture on contact surfaces - reduces resistance.
  • Larger contact areas - reduce resistance.
  • Lower resistance of body portions - increases current flow.

Human Resistance to Electrical Current (External and Internal resistance)

• Skin resistance varies greatly depending on its dryness (wet skin has less resistance).
• External and internal body resistances are key factors in determining the severity of shock.

How About This Scenario?

• Example illustrating how different scenarios affect the likelihood and magnitude of an electrical shock.

This quiz covers the fundamental principles of electricity, including the structure of atoms, specifically focusing on the copper atom. Learn about free electrons and their role in electricity, along with the characteristics of conductors. Perfect for those studying basic electrical concepts.