078 – Static electricity

This lab explores the phenomenon of static electricity by examining the electrification of objects through friction and their interactions when placed near one another. By observing the behavior of charged polyethylene and acetate strips, students will develop an understanding of the fundamental principles of electrostatics, including attraction, repulsion, and the transfer of charges.

Educational Goals

  • Understand static electricity: Learn how objects become charged through friction and how charges influence interactions between objects.
  • Investigate attraction and repulsion: Observe the behavior of charged objects and identify patterns of attraction and repulsion based on the type of charge.
  • Explore material properties and charge transfer: Study how different materials, such as polyethylene, acetate, wool, and cotton, gain or lose electrons through friction.
  • Develop observation and documentation skills: Record detailed observations of object behavior and draw conclusions based on experimental results.
  • Relate experimental findings to theoretical principles: Use an electrostatic series to explain charge transfer and interactions between charged objects.

Protocol

Static electricity

  1. Hang a clamp at the top of each universal stand; as high as possible.
  2. Suspend a rigid movable rod on each clamp.
  3. Hang a blue polyethylene ball on each rigid stem.

Transfer of static electricity between a wool ball and a polyethylene ball.

  1. Take the gray wool ball and bring it close to the blue polyethylene ball suspended from the rod of the left stand. Wait a few seconds for the blue polyethylene ball to become charged with static electricity (it will be attracted to the gray wool ball).
  2. Then bring the gray wool ball close to the second blue polyethylene ball on the right. Wait a few seconds for the blue polyethylene ball to become charged with static electricity (it will be attracted to the gray wool ball).

Reaction between two polyethylene balls charged with static electricity

  1. Unhook the blue polyethylene ball on the left and, without letting the two balls touch, bring this ball close to the one suspended on the right. The observations are recorded in the results table. Then wait until the balls no longer interact with each other.

Transfer of static electricity between a cotton ball and an acetate ball.

  1. Place the blue polyethylene ball; and take the gray wool ball again and gently bring it close to the suspended blue polyethylene ball on the right. Wait a few seconds for the blue polyethylene ball to become charged with static electricity (it will be attracted to the gray wool ball).
  2. Hang a pink acetate ball on the rigid stem on the left.
  3. Take the green cotton ball and gently bring it closer to the pink acetate ball suspended on the left. Wait a few seconds for the pink acetate ball to become charged with static electricity (it will be attracted to the green cotton ball).

Reaction between an acetate ball and a polyethylene ball charged with static electricity.

  1. Detach the pink acetate ball and, without letting the two balls touch, bring this ball close to the suspended blue polyethylene ball. The observations are recorded in the results table. Then wait until the balls no longer interact with each other.

Transfer of static electricity between a wool ball and acetate balls.

  1. Hang the pink acetate ball back on the left.
  2. Unhook and place the blue polyethylene ball on the right.
  3. Hang the second pink acetate ball on the rigid stem available on the right.
  4. Take the gray wool ball and gently bring it close to the pink acetate ball suspended on the left. Wait a few seconds for the pink acetate ball to become charged with static electricity (it will be attracted to the gray wool ball).
  5. Take the same gray wool ball and gently bring it close to the pink acetate ball suspended on the right. Wait a few seconds for the pink acetate ball to become charged with static electricity (it will be attracted to the gray wool ball).

Reaction between two acetate balls charged with static electricity

  1. Detach the pink acetate ball on the left and, without letting the two balls touch, bring this ball close to the one suspended on the right. The observations are recorded in the results table. Then wait until the balls no longer interact with each other. Note: If the reaction between the balls does not work, repeat the previous steps to properly load the balls.
  2. Unhook and set down the pink acetate balls; the stems and the clamps.

Anticipated Outcomes

  • Behavior of charged polyethylene strips
  • Two polyethylene strips rubbed with wool will repel each other, as they acquire the same type of charge (negative). The wool cloth will attract the polyethylene strip due to opposite charges.
  • Behavior of charged acetate strips
  • Two acetate strips rubbed with cotton will repel each other, as they acquire the same type of charge (positive). The cotton cloth will attract the acetate strip due to opposite charges.
  • Understanding charge transfer
  • The polyethylene strip becomes negatively charged by gaining electrons, while the wool cloth becomes positively charged by losing electrons. The acetate strip becomes positively charged by losing electrons, while the cotton cloth becomes negatively charged by gaining electrons.
Results Table
Suspended Object Approached Object Observed Behavior
Polyethylene (wool-rubbed) Wool cloth Attraction
Polyethylene (wool-rubbed) Polyethylene (wool-rubbed) Repulsion
Acetate (cotton-rubbed) Cotton cloth Attraction
Polyethylene (wool-rubbed) Acetate (cotton-rubbed) Attraction
Acetate (cotton-rubbed) Acetate (cotton-rubbed) Repulsion
Significance:
  1. Exploration of fundamental electrostatic principles
    This lab provides a hands-on introduction to static electricity, emphasizing the behavior of charged objects and their interactions.
  2. Application of the electrostatic series
    Students learn to use the electrostatic series to predict and explain the behavior of different materials during frictional charging.
  3. Understanding real-world phenomena
    The experiment connects theoretical principles to common occurrences of static electricity, such as clothing clinging or hair standing up after rubbing.
  4. Development of observation and analytical skills
    By documenting results and interpreting patterns, students enhance their ability to conduct and analyze experiments systematically.
Lessons Learned
  1. Attraction and repulsion in static electricity
    Students observe that like charges repel and opposite charges attract, reinforcing the fundamental principles of electrostatics.
  2. Charge transfer through friction
    The lab demonstrates how rubbing objects with different materials results in charge transfer, leading to specific electrostatic behaviors.
  3. Use of the electrostatic series
    Students learn to predict charge distribution based on the electrostatic properties of materials.
  4. Application of theoretical principles
    The experiment bridges theory and practice, helping students understand and explain electrostatic interactions in physical terms.
  5. Impact of material properties
    Observing the behavior of polyethylene and acetate emphasizes how material properties influence charge transfer and interactions.
  6. Connection to everyday experiences
    The lab encourages students to relate their findings to real-world examples, enhancing their appreciation for the relevance of physics in daily life.

This lab offers a comprehensive introduction to static electricity, providing students with theoretical insights and practical skills for understanding and analyzing electrostatic phenomena.

Summary of Assignment by Grade Range

Grades 6-8 (Middle School):

  • Focus: Introduction to static electricity and basic observations of charged object behavior.
  • Activities: Rub objects, observe interactions, and record data in the results table.
  • Learning Outcomes:
    • Understand the basics of charge transfer through friction.
    • Identify patterns of attraction and repulsion between charged objects.

Grades 9-10 (Junior High School):

  • Focus: Exploration of material properties and charge interactions.
  • Activities: Investigate the behavior of polyethylene and acetate strips when charged, and relate findings to theoretical principles.
  • Learning Outcomes:
    • Analyze the relationship between material type and charge transfer.
    • Develop skills in systematic observation and documentation.

Grades 11-12 (High School):

  • Focus: Advanced analysis of electrostatic interactions and theoretical explanations.
  • Activities: Perform detailed observations, apply the electrostatic series to explain results, and evaluate experimental accuracy.
  • Learning Outcomes:
    • Master the concept of charge transfer and its dependence on material properties.
    • Relate experimental findings to real-world applications, such as static electricity in everyday life.

Laboratory essentials

Instruments

  • Sticks
  • Lab stands
  • Clamps

Products

  • 2 polyethylene strips
  • 2 acetate strips
  • Wool fabric
  • Cotton fabric