Week 17 Lab Electric Charges

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50-0236-pk-02-lab_manual_1.pdf

Physics LabPaq / Published by: Hands-On Labs, Inc.

[email protected] / www.HOLscience.com / Toll Free 866.206.0773

A Laboratory Manual of small-scale Experiments for the independent study of Physics

LabPaq® is a registered trademark of Hands-On Labs, Inc. (HOL). The LabPaq referenced in this manual is produced by Hands-On Labs, Inc. which holds and reserves all copyrights on the intellectual properties associated with the LabPaq’s unique design, assembly, and learning experiences. The laboratory manual included with a LabPaq is intended for the sole use by that LabPaq’s original purchaser and may not be reused without a LabPaq or by others without the specific written consent of HOL. No portion of any LabPaq manual’s materials may be reproduced, transmitted or distributed to others in any manner, nor may be downloaded to any public or privately shared systems or servers without the express written consent of HOL. No changes may be made in any LabPaq materials without the express written consent of HOL. HOL has invested years of research and development into these materials, reserves all rights related to them, and retains the right to impose substantial penalties for any misuse.

Published by: Hands-On Labs, Inc. 3880 S. Windermere St. Englewood, CO 80110

Phone: Denver Area: 303-679-6252 Toll-free, Long-distance: 866-206-0773

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Printed in the United States of America.

The experiments in this manual have been and may be conducted in a regular formal laboratory or classroom setting with the users providing their own equipment and supplies. However, this manual was especially written for the benefit of the independent study of students who do not have convenient access to such facilities. It allows them to perform college and advanced high school level experiments at home or elsewhere by using a LabPaq, a collection of experimental equipment and supplies specifically packaged to accompany this manual.

Use of this manual and authorization to perform any of its experiments is expressly conditioned upon the user reading, understanding and agreeing to fully abide by all the safety precautions contained herein.

Although the author and publisher have exhaustively researched many sources to ensure the accuracy and completeness of the information contained in this manual, we assume no responsibility for errors, inaccuracies, omissions or any other inconsistency herein. Any slight of people, organizations, materials, or products is unintentional.

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50-0236-PK-02

Table of contents 5 To the instructor

6 To the student

7 how to Perform an Experiment

9 safety concerns

11 science Lab safety Reinforcement Agreement

Experiments 14 Static Electricity or Electrostatics

28 Electric Fields

38 Introduction to Electrical Circuits: Ohm’s Law

52 Resistors in series and Parallel

77 semiconductor Temperature sensor

86 capacitance in a circuit

103 Electric Motor

111 Reflection and Refraction

127 Diffraction Grating

142 Polarized Light

150 Radioactive Decay

APPENDiX 160 Laboratory Equipment and Techniques

161 Potential Laboratory Hazards

162 Use, Disposal, and Cleaning Instructions for Common Materials

163 Material safety Data sheets

165 how to Write Lab Notes and Lab Reports

171 Laboratory Drawings

173 Digital Multimeter Instructions

177 Final Cleanup Instructions

179 Using Statistics

183 The T-Test

189 The chi-square Test

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To the instructor As an increasing number of students embrace online and independent-study courses, laboratory experiences must remain an integral part of science education. This lab manual’s author and publisher are science educators who welcome electronic technology as an effective tool to expand and enhance instruction. However, technology can neither duplicate nor replace learning experiences afforded to students through traditional hands-on laboratory and field activities. This does not mean that some experiments cannot or should not be replaced or reinforced by computer simulations; but any course of science study must also provide sufficient hands-on laboratory and field experiences to:

● Engage students in open-ended, investigative processes by using scientific problem solving.

● Provide application of concepts students have seen in their study materials, which reinforce and clarify scientific principles and concepts.

● Involve multiple senses in three-dimensional rather than two-dimensional learning experiences that are important for greater retention of concepts and for accommodation of different learning styles.

● Stimulate students to understand the nature of science including its unpredictability and complexity.

● Provide opportunities to engage in collaborative work and to model scientific attitudes and behavior.

● Develop mastery of techniques and skills needed for potential science, engineering, and technology careers.

The knowledge gained from science courses with strong laboratory components enables students to understand, in practical and concrete ways, their own physical makeup, the functioning of the natural world around them, and contemporary scientific and environmental issues. It is only by maintaining hands-on laboratory experiences in our curricula that the brightest and most promising students will be stimulated to learn scientific concepts and avoid being turned-off by lecture- and textbook-only approaches. Physical experimentation may offer some students their only opportunity to experience a science laboratory environment. All students – as potential voters, parents, teachers, leaders, and informed citizens – will benefit from a well-rounded education that includes science laboratory experiences when it is time for them to make sound decisions affecting the future of their country and the world.

This lab manual can be used by all students, regardless of the laboratory facilities available to them. The experiments are based on the principles of micro-scale science which have been successfully used in campus laboratories for decades. LabPaq’s micro-scale experiments can also be performed at home, in a dorm room, or at a small learning center that lacks a formal laboratory.

Introduction

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To the student Science is a way of learning about our natural world and how it works by testing ideas and making observations. Learning about the characteristics of the natural world and how those characteristics change and interact with each other makes it easier to understand ourselves and our physical environment. Also, it helps us make the multitude of personal and global decisions that affect our lives and our planet. Science credits are impressive on an academic transcript and your science knowledge may create some unique job opportunities.

What are Micro-scale Experiments?

You may be among the growing number of students to take a full-credit, laboratory science course through independent study, due to the development and perfection of micro-scale and small- scale experimentation techniques over the past half century. While experimentation on any scale is foundational to fully understanding science concepts, science courses in the past have required experimentation to be performed in the campus laboratory due to the potential hazards inherent in traditional experimentation.

Potential hazards, increasing chemical, specimen, and science equipment costs, and environmental concerns made high schools, colleges, and universities reexamine the traditional laboratory methods used to teach science. Scientists began to scale down the quantities of materials and the size of equipment used in experiments and found reaction results remained unchanged.

Over time, more and more traditional science experiments were redesigned to be performed on micro and small scales. Educational institutions eventually recognized that the scientific reaction, not the size of the reaction, facilitates learning. Successive comparative assessments have proven that students’ learning is not impaired by studying small-sized reactions. Many assessments even suggest that science learning is enhanced by small-scale experimentation.

In the mid-1990s, Dr. Peter Jeschofnig of Colorado Mountain College, pioneered the development of LabPaqs: academically aligned, small-scale experiments that can be performed at home. Hands-On Labs, Inc. has subsequently proven that students can perform LabPaq’s rigorous science experiments at home and still achieve an equivalent, if not higher, level of learning than their campus-based peers.

Introduction

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how to Perform an Experiment Although each experiment is different, the process of preparing, performing, and recording an experiment is essentially the same.

Choose the Right Place for Your Home Laboratory: The best place to perform at-home experiments will be determined by the nature of the individual experiments. However, this place is usually an uncluttered room where a door can be closed to keep out children and pets; a window or door can be opened for fresh air, ventilation, and fume exhaust; there is a source of running water for fire suppression and cleanup; and there is a counter or tabletop work surface. A kitchen usually meets all these requirements. Sometimes the bathroom works too, but it can be cramped and subject to interruptions.

Review each experiment before starting any work to help you select the most appropriate work area. Because some of the equipment and supplies in your LabPaq may pose dangers to small children and animals, always keep safety in mind when selecting a work area, and always choose an area where you cannot be disturbed by children or pets.

Use a Lab Partner: While the experiments in the LabPaq can be performed independently, it is often fun and useful to have a lab partner to discuss ideas with, help take measurements, and reinforce your learning process. Whether your partner is a parent, spouse, sibling, or friend, you will have to explain what you are doing, and in the process of teaching another, you will better teach yourself. Always review your experiments several days ahead of time so you have time to line up a partner if needed.

Read the Entire Experiment before You Start: Knowing what you are going to do before you do it will help you organize your work and be more effective and efficient.

Review Basic Safety: Before beginning work on any experiment, reread the lab manual’s safety sections, try to foresee any potential hazards, and take appropriate steps to prevent safety problems.

Organize Your Work Space, Equipment, and Materials: It is hard to organize your thoughts in a disorganized environment. Assemble all required equipment and supplies before you begin working.

Outline Your Lab Notes: Outline the information needed for your Lab Notes and set up any required data tables before the experiment, to make it easier to enter observations and results as they occur. LabPaq CDs normally include a Report Assistant containing .rtf files of each experiment’s questions and data tables. These files can be copied and pasted into your Lab Notes to facilitate your compilation of data and text information.

Perform the Experiment According to Instructions: Follow all directions precisely in sequential order. This is not the time to be creative. Do not attempt to improvise your own procedures!

Introduction

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Think About What You Are Doing: Stop and give yourself time to reflect on what has happened in your experiment. What changes occurred? Why? What do they mean? How do they relate to the real world of science? This step can be the most fun and often creates “light bulb” experiences of understanding.

Cleanup: Always clean your laboratory space and laboratory equipment immediately after use. Wipe down all work surfaces that may have been exposed to chemicals or dissection specimens. Blot any unused chemicals with a paper towel or flush them down the sink with generous amounts of water. Wrap dissection specimens in newspaper and plastic and place them in a sealed garbage can. Discard used pipets and other waste in your normal trash. Return cleaned equipment and supplies to their LabPaq box and store the box out of reach of children and pets.

Complete Your Work: Complete your Lab Notes, answer the required questions, and prepare your Lab Report. If you have properly followed all the above steps, the conclusion will be easy.

NOTE: The Appendix section of this manual contains valuable information regarding equipment and techniques specific to the discipline you are studying. Please take the time to review this section before beginning experimentation.

Introduction

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safety concerns CAUTION for Women:

If you are pregnant or could be pregnant, you should seek advice from your personal physician before doing any type of science experimentation.

You, as a responsible science student and researcher, are solely responsible for safely storing and using your LabPaq materials and for conducting your experiments in a safe and responsible manner.

Items in your LabPaq can be especially dangerous to children and pets, so the LabPaq should always be kept safely stored out of their reach. The LabPaq may contain acids or other chemicals that can cause burns if mishandled plus serious illness and/or death if consumed.

Many LabPaq items are made of glass and/or have sharp edges that pose potential risks for cuts and scratches. While LabPaq thermometers do not contain mercury, they might still break and cause injury. LabPaqs contain small items and materials that could cause choking, injury, or death if misused.

Experimentation may require you to climb, push, pull, spin, and whirl. While these activities are not necessarily dangerous, they can pose hazards which means you should always undertake these activities cautiously and with consideration for your surroundings. If you need to climb to take measurements, make sure any stool, chair, or ladder you use is sturdy and take ample precautions to prevent falls. It is wise to have a partner help keep you stable when you must climb. Be especially aware of experimental equipment that you must put in motion, and act cautiously to ensure that items cannot go astray and cause injury to people or property.

If you or anyone accidentally consumes or otherwise comes into contact with a substance that could be toxic or cannot be easily washed away, immediately call:

The National Poison Control Center: 1-800-222-1222

Your eyesight is precious and should be protected against chemical spills or splashes as well as flying objects and debris. Always wear safety goggles when working with chemicals of any kind and when working with non-chemical objects that could possibly fly into your eyes.

Since chemicals, dirt, and germs are often involved in laboratory experiments, you should never eat or smoke in your laboratory area. Protect your body by keeping your hair tied back from your face and by wearing old clothing that fully covers your arms, legs, and feet.

You also need to protect your home furnishings from damage during your experimentation. Cover your work surface with plastic or paper towels when appropriate to prevent ruining furniture and to aid in cleanup.

Introduction

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The best safety tools you have are your own mind and intellectual ability to think and plan. After previewing each experiment, carefully think about what safety precautions you need to take to experiment safely, and then take them!

Since it is impossible to control students’ use of this lab manual and related LabPaqs or students’ work environments, the author(s) of this lab manual, the instructors and institutions that adopt it, and Hands-On Labs, Inc. – the publisher of the lab manual and the producer of LabPaqs – authorize the use of these educational products only on the express condition that the purchasers and users accept full and complete responsibility for all and any liability related to their use of same. Additional terms authorizing the use of a LabPaq are contained in its Purchase Agreement available at www.HOLscience.com.

Introduction

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science Lab safety Reinforcement Agreement Any type of science experimentation involves potential hazards, and unforeseen risks may exist. The need to prevent injuries and accidents cannot be overemphasized!

Use of this lab manual and any LabPaqs are expressly conditioned upon your agreement to follow all safety precautions and accept full responsibility for your actions.

Study the safety section of this lab manual until you can honestly state the following:

 Before beginning an experiment, I will first read all directions and then assemble and organize all required equipment and supplies.

 I will select a work area that is inaccessible to children and pets while experiments are in progress. I will not leave experiments unattended and I will not leave my work area while a chemical equipment is set up unless the room is locked.

 To avoid the potential for accidents, I will clear my home laboratory workspace of all non-laboratory items before setting up equipment and supplies for my experiments.

 I will never attempt an experiment until I fully understand it. If in doubt about any part of an experiment, I will first speak with my instructor before proceeding.

 I will wear safety goggles when working with chemicals or items that can get into my eyes.

 I know that except for water, most solvents, such as toluene, alcohols, acetone, ethers, and ethyl acetate are highly flammable and should never be used near an open flame.

 I know that the heat created when water is added to concentrated acids is sufficient to cause spattering. When preparing dilute acid solutions, I will always add the acid to the water – rather than the water to the acid – while slowly stirring the mixture.

 I know it is wise to wear rubber gloves and goggles when handling acids and other dangerous chemicals; I should neutralize acid spills with sodium bicarbonate; and I should wash acid spilled on skin or clothes immediately with plenty of cold water.

 I know that many chemicals produce toxic fumes and that cautious procedures should be used when smelling any chemical. When I wish to smell a chemical, I will never hold it directly under my nose, but will use my hand to waft vapors toward my nose.

 I will always handle glassware with respect and promptly replace any defective glassware. Even a small crack can cause glass to break, especially when heated. To avoid cuts and injuries, I will immediately dispose of any broken glassware.

 I will avoid burns by testing glass and metal objects for heat before handling. I know that the preferred first aid for burns is to immediately hold the burned area under cold water for several minutes.

Introduction

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 I know that serious accidents can occur when wrong chemicals are used in an experiment. I will always read labels before removing chemicals from their containers.

 I will avoid the possibility of contamination and accidents by never returning an unused chemical to its original container. To avoid waste I will try to pour only the approximate amount of chemicals required.

 I know to immediately flush any chemical spill on the skin with cold water and consult a doctor if required.

 To protect myself from potential hazards, I will wear long pants, a long-sleeved shirt, and enclosed shoes when performing experiments. I will tie up any loose hair, clothing, or other materials as well.

 I will never eat, drink, or smoke while performing experiments.

 After completing all experiments, I will clean my work area, wash my hands, and store the laboratory equipment in a safe place inaccessible to children and pets.

 I will always conscientiously work in a reasonable and prudent manner to optimize my safety and the safety of others whenever and wherever I am involved with any type of science equipment or experimentation.

I am a responsible adult who has read, understands, and agrees to fully abide by all safety precautions prescribed in this lab manual for laboratory work and for the use of a LabPaq. Accordingly, I recognize the inherent hazards associated with science experimentation; I will always experiment in a safe and prudent manner; and I unconditionally accept full and complete responsibility for any and all liability related to my purchase and/or use of a science LabPaq or any other science products or materials provided by Hands-On Labs, Inc. (HOL).

____________________________________________________ ____________ Student’s Name (print) and Signature Date

Introduction

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LabPaq by Hands-On Labs

ExpErimEnts

Static Electricity or Electrostatics Peter Jeschofnig, Ph.D. Version 42-0278-00-01

Review the safety materials and wear goggles when working with chemicals. Read the entire exercise before you begin. Take time to organize the materials you will need and set aside a safe work space in which to complete the exercise.

Experiment Summary:

Students will explore the concepts of static electricity, discover how many types of electrical charges exist, and observe how they interact with each other. They will learn how static electricity is generated and how materials are ranked through the triboelectric series. Students will conduct various experiments to explore static electricity.

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ExpErimEnt

Objectives ● To explore the concepts of static electricity and to discover how many types of electrical

charges exist and how they interact with each other

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Experiment Static Electricity or Electrostatics

materials

MATERIALS FROM QTy ITEM DESCRIPTION Student Provides 1 Scrap of white paper 1 Transparent tape

From LabPaq 1 Aluminum Foil - 6"x 6" 2 Cup, Styrofoam, 8 oz 1 Dark paper - 1/2 Sheet 1 Ruler, Metric

Fabrics Bag 1 Fabric Swatch-5 pieces-PK 1 Rabbit fur, swatch - 4"x2"

Misc. Supplies Bag 2 Balloons 1 Pepper Packets 1 Salt Packets 1 Thread for PK-2/S 1M per kit

Note: The packaging and/or materials in this LabPaq may differ slightly from that which is listed above. For an exact listing of materials, refer to the Contents List form included in the LabPaq.

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Experiment Static Electricity or Electrostatics

Discussion and review We all experience static electricity in our everyday lives. Perhaps we feel a shock when we touch a doorknob after walking across a wool rug. Or perhaps we see the static cling of plastic food wrap as it hugs a bowl or feel the buzz of static electricity when we run our fingers across a television or computer screen. Most of our encounters with static electricity are surprising but not harmful; however, we sometimes hear stories about it destroying computer chips and starting fires.

When we tumble clothes in a dryer without a fabric softener, different articles of clothing such as a sweaters, socks, and underwear stick to each other. Why? This occurs because one item gained negative charges from another item that became positively charged by giving up electrons. The charges gained are strong enough to produce an attractive force that keeps the clothes stuck together. In this situation we say that the items have become “electrified” or electrically “charged.”

It is often difficult for students to remember that an atom becomes positively charged when it gives up an electron. This seems counter intuitive for when we lose something, it is usually a negative event. Here’s a corny joke to help you remember this concept. Two atoms are walking down the street and one exclaims, “Oh my, I think I’ve lost an electron!” The other asks, “Are you sure? “ The first replies, “Yes, I’m positive!”

When you walk or vigorously rub your shoes across a wool rug, your body becomes electrified. The charge that builds up on your body will be removed when you touch another object such as a door handle, light switch, or even a person. Sometimes it will produce a noticeable spark and a little unpleasant shock. Lightning is a dramatic display of how built-up charges are removed. Charges between clouds and the ground build up and become very high. The release of these massive charges is more than just a spark; it is a bolt of lightning that can do a lot of damage!

Two types of electric charges exist in nature: A positive charge like the charge of a proton, and a negative charge like the charge of an electron. Charged objects have an imbalance of protons and electrons. There is a connection between the type of charge on an object and the type of interaction it has with other objects. The interactions possible are attraction, repulsion, and none. Charges of the same type repel each other, while charges of different types attract each other. This basic law is simply stated: Like charges repel. Unlike charges attract.

Charges are produced in three basic ways:

● Friction: People have long known that rubbing items together or tearing them apart quickly could produce a charge; this is called charging by friction.

● Induction: An induced charge is created when an electrically charged item near a conductor causes a redistribution of charges on the conductor.

● contact: A third way to charge conductors - which are usually metals - is by contact where the charge spreads around all the conductors in contact.

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Experiment Static Electricity or Electrostatics

Triboelectric Series: When two different materials are rubbed together, one will become positively charged and one will become negatively charged. Materials have been ranked based on their propensity to accept or give up electrons, and this ordering or ranking is referred to as the triboelectric series. To the right is a simplified table of some common materials. Typically, materials higher on the list are more likely to give up electrons and become positively charged when rubbed with materials below them on the list.

In a systematic series of simple experiments, one can determine the existence of charges and the forces produced due to them. You may have noticed that transparent tape like Scotch® tape, or plastic wrap, like Glad Wrap frequently sticks to your hand when you handle it. This is static electricity at work.

General comments about this lab:

● When instructed to “rub,” vigorous rubbing is required.

● Make certain that you test the area you actually rubbed. When you rub one end of a ruler, test that end, not the other!

● Electrostatic experiments are hard to perform on humid days. Schedule your lab work accordingly.

● Sometimes the results of this lab can be inconsistent. It is therefore suggested that each step is performed several times and that observations are recorded after you are sure of the your observations. Take your time, you will find this is a fun lab!

TRIBOELECTRIC SERIES

Your Hand Glass

Your Hair Nylon Wool Fur Silk

Paper Cotton

Hard Rubber Polyester

Polyvinylchloride Plastic

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Experiment Static Electricity or Electrostatics

procedure Caution: The levels of static electricity used in this lab will not hurt an individual but they may be high enough to impact or ruin calculators, computers, and other electronic equipment with solid state components. Accordingly, do not conduct these experiments next to such electronic equipment.

Part i

1. From white scrap paper, cut or tear at least 10 very small pieces of approximately 1-cm squares. Scatter these on a piece of dark-colored paper that rests on top of a work table or desk. Then sprinkle a small amount of salt and pepper on the colored paper; several shakes should work fine. Align a plastic ruler parallel to the desktop, just barely above the colored paper and slowly move the ruler back and forth. Observe what happens and record your observations.

2. Next, “charge” the ruler. To do this, wrap a piece of fabric around two sides of the ruler. Hold the material and ruler firmly between your thumb and fingers in one hand and with the other hand vigorously rub the ruler back and forth for about 5 seconds. Then slowly move the charged ruler over the paper, salt, and pepper. Observe what happens and record your observations.

3. Repeat step 2 after charging the ruler with each of the different types of material. Record your observations.

4. Predict what …