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# Polarization

This lesson aligns with Next Generation Science Standards (NGSS) PS3.C

Introduction
Have you ever experienced the surprising sensation of a sudden shock when touching a metal object or noticed your hair standing on end after removing a hat? These intriguing occurrences are a result of static electricity. It is a fascinating phenomenon that often leaves us with more questions than answers. In this article, we will explore the concept of polarization and its pivotal role in static electricity and static discharge. By understanding these electrifying phenomena, we will uncover the secrets behind the mysterious effects of static electricity.

What is Polarization?
Polarization is the process by which the electric field within a material becomes aligned in a specific direction. It occurs when an external electric field is applied to a material, causing the positive and negative charges within the material to separate and align themselves accordingly. Polarization is closely related to the concept of electric dipoles, which are pairs of positive and negative charges separated by a small distance.

Static Electricity and Static Discharge

Static Electricity
Static electricity refers to the accumulation of electric charges on the surface of objects. In other words, polarization leads to the buildup of electric charges on objects, this buildup of charges is known as static electricity.

Built-up of Static Electricity
It occurs when two objects come into contact and then separate, causing the transfer of electrons between them. This transfer of electrons creates an imbalance of charges, leading to the phenomena we associate with static electricity, such as sparks, shocks, and the attraction or repulsion of objects.

Static Discharge
Let us consider again the example of our hand and the metal doorknob. When a negatively charged hand gets very close to the doorknob that is positively charged, the air between our hand and the knob may become electrically charged. If that occurs, it allows electrons to suddenly flow from our hand to the knob. This is the electric shock we suddenly feel when we touch the knob. It may even spark as the electrons jump from the hand to the metal. This sudden flow of electrons is called static discharge.

Role of Polarization in Static Electricity
Polarization plays a crucial role in the build-up and discharge of static electricity. Let's explore its role in each of these processes.

Polarization facilitates the build-up of static electricity in the following way:
• When the objects initially come into contact, the electric fields of the two objects influence each other. The charges within the objects redistribute themselves due to the polarization effect.
• As the objects separate, the charges become temporarily locked in their positions. This causes one object to acquire a positive charge (due to an electron deficiency) and the other object to acquire a negative charge (due to an excess of electrons).
• The separation of charges creates an electric field between the objects, which is responsible for the attractive or repulsive forces observed in static electricity.
• If the potential difference between the charged object and the other object or conductor is significant, the charges may rapidly flow across the gap. It equalizes the charge distribution. This flow of charges is often observed by a spark or a sudden shock.

Practical Applications of Polarization and Static Discharge
The phenomena of polarization and static discharge have various practical applications in different fields. Some notable examples include:

Lightning Protection Systems
Polarization and the discharge of static electricity play a crucial role in lightning protection systems. Lightning rods are designed to safeguard structures from lightning strikes. They work by polarizing the surrounding air and providing a path of least resistance for the discharge of lightning's electrical energy.

Photocopiers and Laser Printers
The imaging process in photocopiers and laser printers relies on the principles of polarization and static discharge. Electrostatic charges are used to attract and transfer toner particles onto paper, resulting in the reproduction of images or text.

Dust and Particle Control
In industries where dust and particles can be hazardous or interfere with processes, static electricity is employed for control. Electrostatic precipitators, for instance, utilize polarization and static discharge to remove particles from exhaust gases or air, enhancing air quality.

Summary
• Polarization is defined as the movement of electrons within a neutral object due to the electric field of a nearby charged object. Polarization occurs without direct contact between the two objects.
• Static electricity refers to the accumulation of electric charges on the surface of objects.
• Static discharge is a sudden flow of electrons from one charged object to another when they come into contact with each other.

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