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Unit 03 — Static Electricity
ELECTRICAL FUNDAMENTALS
Static Electricity
Static electricity is the buildup of electric charge on the surface of an object. Understanding how charges are created, transferred, and discharged helps explain sparks, shocks, grounding, and many electrical hazards.
01
What Is Static Electricity?
Static electricity is an imbalance of electric charge.
ELECTRIC CHARGE Positive and Negative Charges Matter contains positively charged protons and negatively charged electrons. In normal conditions, an object has equal numbers of positive and negative charges and is electrically neutral.
ELECTRON TRANSFER Gaining or Losing Electrons Static charge is commonly produced when electrons move from one material to another. An object that gains electrons becomes negatively charged. An object that loses electrons becomes positively charged.
CHARGE BEHAVIOR Like Charges Repel Charges with the same polarity repel each other. Positive charges repel positive charges, and negative charges repel negative charges.
CHARGE BEHAVIOR Opposite Charges Attract Positive and negative charges attract each other. This attraction is one of the basic behaviors of electric charge.
02
Producing Static Charge
Static electricity can be created in several ways.
FRICTION Friction Rubbing two different materials together can cause electrons to transfer from one material to another. Walking across a carpet is a common example.
CONTACT Conduction A charged object can transfer electrons to another object when the two objects come into contact.
INDUCED CHARGE Induction A nearby charged object can cause the charges inside another object to separate or redistribute without direct contact.
03
Conductors and Insulators
Materials respond differently to electric charge.
CONDUCTORS Conductors Conductors contain electrons that can move relatively freely. Copper, aluminum, and other metals are common electrical conductors.
INSULATORS Insulators Insulators hold their electrons more tightly and resist the movement of electric charge. Rubber, glass, plastic, and dry wood are common examples.
ELECTRICIANS Why This Matters Conductors provide paths for charge to move, while insulation helps prevent unwanted current from reaching people or other conductive surfaces.
04
Static Discharge
Static charge remains until it has a path to move.
DISCHARGE What Causes a Spark? When enough charge builds up, the electrical potential difference can become large enough for electrons to move through the air. The sudden movement of charge can produce a visible spark.
EXAMPLE Static Shock A person can build up static charge while walking across a carpet. Touching a conductive object can provide a path for the charge to discharge, producing a small shock.
HUMIDITY Dry Air Static electricity tends to build up more easily in dry conditions because moisture in the air can help charge dissipate.
05
Grounding and Static Charge
Grounding provides a path for unwanted electrical charge.
GROUND Earth as a Reference The earth can absorb or supply electrons without becoming significantly charged. Electrical systems use grounding to establish a reference point and provide paths for fault current.
BONDING Bonding Conductive Parts Bonding connects conductive parts together so they remain at substantially the same electrical potential and helps provide a low-impedance path for fault current.
SAFETY Preventing Unwanted Discharge Proper grounding, bonding, and static-control procedures can reduce the risk of unexpected discharge and protect sensitive electrical and electronic equipment.
06
Electrical Safety
Static electricity can create hazards in certain electrical environments.
IGNITION HAZARD Flammable Materials A static spark can ignite certain flammable vapors, gases, or dust. Static-control procedures are especially important where combustible materials are present.
ELECTRONICS Electrostatic Discharge Electrostatic discharge, or ESD, can damage sensitive electronic components even when the discharge is too small to be noticed by a person.
WORK PRACTICE Static-Control Procedures Grounding wrist straps, conductive work surfaces, antistatic materials, and proper handling procedures can help control static charge when working with sensitive electronics.
07
Quick Review
Key points to remember.
REMEMBER Electrons Create Charge Imbalance Static charge is primarily caused by an object gaining or losing electrons.
REMEMBER Like Repels, Opposites Attract Charges with the same polarity repel. Charges with opposite polarity attract.
REMEMBER Static Charge Can Discharge When a conductive path becomes available, accumulated static charge can move suddenly from one object to another.
REMEMBER Grounding Provides a Path Grounding and bonding help control electrical potential and provide paths for unwanted electrical current.
NEXT UNIT
Unit 04 — Magnetism
Continue studying the relationship between electricity and magnetism, including magnetic fields, electromagnetism, and electromagnetic force.