Ask Investigable Questions About Factors That Influence Electric and Magnetic Force Strength - Middle School Physical Science

SECTION 1

Historical Context & Motivation

Have you ever rubbed a balloon on your hair and watched it stick to a wall? Or held two magnets and felt them snap together or push apart? People have wondered about these invisible forces for thousands of years. The story of how scientists figured out electric forces (pushes and pulls between charged objects) and magnetic forces (pushes and pulls between magnets or moving charges) is full of curious people asking great questions.

~600 BCE • Ancient Greek Observations

Thales of Miletus noticed that rubbing amber with fur attracted lightweight objects. He also observed that a special rock called lodestone (a naturally magnetic mineral) could pull iron toward it.

1600 • William Gilbert's Experiments

English scientist William Gilbert carefully tested which materials could be charged by rubbing. He asked a key question: "Are electric and magnetic forces the same thing?" His experiments showed they were different.

1785 • Coulomb Measures Electric Force

Charles-Augustin de Coulomb built a device to measure how electric force changes with distance and charge amount. He discovered that force gets weaker as objects move farther apart.

1820 • Ørsted Connects Electricity and Magnetism

Hans Christian Ørsted noticed a compass needle moved when he turned on an electric current nearby. This proved that electricity and magnetism are related—a huge discovery!

1831 • Faraday's Field Lines

Michael Faraday used iron filings to visualize magnetic fields. He showed that the strength of the force depends on how close together the field lines are.

Every one of these breakthroughs started with a question someone could actually test. In this lesson, you will learn how to ask investigable questions about what makes electric and magnetic forces stronger or weaker. An investigable question is one you can answer by collecting data through observation or experiment.

SECTION 2

Core Principles & Key Definitions

Before you can ask good questions, you need to understand the basics. Electric and magnetic forces are both non-contact forces (forces that act without objects touching). They can attract or repel objects across a distance. Scientists use a framework called three-dimensional learning in the NGSS. This means we combine science content, science practices, and big-picture patterns.

Electric Force

The push or pull between objects that have an electric charge (a property caused by having extra or missing electrons). Like charges repel; opposite charges attract.

Magnetic Force

The push or pull between magnets or between a magnet and certain metals. Every magnet has a north pole and a south pole. Opposite poles attract; same poles repel.

Investigable Question

A question that can be answered by designing an experiment, collecting data, and analyzing results. It identifies a variable (something you can change or measure).

Force Strength

How strong a push or pull is. We can measure force strength in newtons (N), the standard unit of force. A stronger force means a bigger number of newtons.

Factors (Variables)

Things that can change and might affect force strength. Examples include distance between objects, amount of charge, and magnet strength.

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KEY TAKEAWAY

Think of an investigable question like a recipe you can actually cook. Asking "Why is gravity weird?" is not investigable because you cannot test it with a simple experiment. But asking "How does the distance between two magnets affect how strongly they pull together?" is investigable—you can set up magnets, change the distance, and measure the force. A good investigable question names what you will change, what you will measure, and what you will keep the same.

SECTION 3

Visualizing Electric & Magnetic Forces

The diagram below shows how electric and magnetic forces change with distance. Notice the pattern: as the objects get farther apart, the force gets weaker. This pattern is called an inverse relationship (when one thing goes up, the other goes down). The diagram also highlights two key factors you can investigate.

This graph shows how force strength (vertical axis) decreases as distance (horizontal axis) increases. The cyan data points curve downward sharply at first, then level off. The pink annotation box shows this is a testable, investigable question.

Look at the cyan curve in the diagram. When the distance is only 2 cm, the force is very strong. By 6 cm, the force has dropped a lot. This pattern shows up for both electric and magnetic forces. It is an example of the crosscutting concept of Cause and Effect: changing distance (the cause) changes force strength (the effect).

SECTION 4

How to Build an Investigable Question

Not all questions are investigable. You need to be able to design a fair test to answer them. A fair test means you change only one independent variable (the thing you change on purpose), measure one dependent variable (the thing you observe or measure), and keep everything else the same. Those things you keep the same are called controlled variables.

The Question-Building Framework

You can use a simple sentence frame to create investigable questions:

QUESTION FRAME

"How does [independent variable] affect [dependent variable]?"

Independent variable = the factor you change (e.g., distance, charge amount, number of magnets). Dependent variable = the result you measure (e.g., force strength in newtons, number of paper clips picked up).

Key Factors That Influence Force Strength

Factor	Applies To	Example Investigable Question
Distance	Electric & Magnetic	How does the distance between two charged balloons affect how strongly they push apart?
Amount of charge	Electric	How does rubbing a balloon more times change how many pieces of paper it can pick up?
Magnet strength	Magnetic	How does using a stronger magnet affect the number of paper clips it can hold?
Number of coils (electromagnet)	Magnetic	How does the number of wire coils around a nail change how many paper clips the electromagnet picks up?
Type of material between objects	Electric & Magnetic	How does placing different materials (paper, plastic, aluminum) between magnets change the force?

Common factors and example investigable questions about electric and magnetic forces

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NGSS Connection: Asking Questions (SEP)

The NGSS Science and Engineering Practice of Asking Questions means you should be able to identify questions that can be investigated within the scope of your classroom. You should also be able to recognize when a question is NOT testable and needs to be revised.

SECTION 5

Investigable vs. Non-Investigable Questions

One of the most important skills in science is telling the difference between a question you can test and one you cannot. Let's look at a diagram that compares the two types. Understanding this difference connects to the crosscutting concept of Patterns: investigable questions follow a clear pattern in how they are worded.

The left column (green border) shows investigable questions that name specific variables. The right column (red border) shows non-investigable questions that are too broad, opinion-based, or untestable. The amber boxes at the bottom highlight the key patterns.

Notice the pattern on the left side. Every investigable question names something specific to change (distance, number of coils, number of rubs, type of material). It also names something to measure (force, strength, number of paper clips). On the right side, the questions are missing one or both of these parts.

✓ Checklist for a good investigable question:
✓ Does it name a specific independent variable (what you change)?
✓ Does it name a dependent variable (what you measure)?
✓ Can you actually do this experiment with your classroom tools?
✓ Is the answer based on data, not opinions?

SECTION 6

Worked Example: Building and Testing a Question

Let's walk through a complete example. Imagine you have two bar magnets and a ruler. You want to know how distance affects force. Here is how a scientist would approach this.

Investigating Magnetic Force vs. Distance

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Step 1 — Start with an Observation (Anchoring Phenomenon)

You notice that when you bring two magnets close together, they snap together hard. But when you hold them far apart, you barely feel anything. This is your anchoring phenomenon—a real-world event that makes you curious.

Observation: Magnets feel stronger when closer.
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Step 2 — Write an Investigable Question

Use the question frame: "How does [independent variable] affect [dependent variable]?" Your independent variable is distance. Your dependent variable is force strength.

Question: "How does the distance between two bar magnets affect the strength of the magnetic force between them?"
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Step 3 — Identify Your Variables

Independent variable: distance between magnets (you will test 1 cm, 3 cm, 5 cm, 7 cm, and 10 cm). Dependent variable: the force, measured by how many paper clips the magnet can hold at each distance. Controlled variables: same two magnets, same paper clips, same surface, same orientation (north-to-south).

Three types of variables identified.
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Step 4 — Plan the Investigation

Place one magnet flat on a table. Use a ruler to set the second magnet at each distance. At each distance, count how many paper clips the second magnet can pick up while being held at that distance. Repeat three times at each distance and calculate the average.

A clear, repeatable experimental plan.
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Step 5 — Predict the Pattern

Based on your observation and what you know about forces, you predict: "As distance increases, the magnetic force will decrease, so the magnet will pick up fewer paper clips." This connects to the crosscutting concept of Cause and Effect.

Prediction: Greater distance → weaker force → fewer paper clips.

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What Comes Next?

After planning, you would collect data, organize it in a table, look for patterns, and construct an explanation from your evidence. The question you asked guided every step of the investigation!

SECTION 7

Comparing Electric and Magnetic Forces

Electric and magnetic forces are related, but they are not the same. Knowing their similarities and differences helps you ask better investigable questions. The crosscutting concept of Systems and System Models reminds us to think about what parts of a system we are investigating.

Feature	Electric Force	Magnetic Force
What causes it?	Electric charges (positive and negative)	Magnetic poles (north and south) or moving charges
Can attract AND repel?	Yes. Opposite charges attract; like charges repel.	Yes. Opposite poles attract; like poles repel.
Affected by distance?	Yes. Force decreases as distance increases.	Yes. Force decreases as distance increases.
Key factor for strength	Amount of charge on each object	Strength of magnets (or amount of current in an electromagnet)
Acts on what materials?	All materials can become charged (some more easily)	Mainly iron, nickel, cobalt, and their alloys
Is it a non-contact force?	Yes	Yes

Comparison of electric and magnetic forces

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KEY TAKEAWAY

Think of electric and magnetic forces like two cousins in the same family. They share common traits—both are non-contact forces that get weaker with distance and can push or pull. But they have different causes: one comes from electric charges, and the other comes from magnetic poles or moving charges. When you write an investigable question, be specific about WHICH force you are studying and WHICH factor you are changing.

SECTION 8

Connecting to More Advanced Ideas

The investigable questions you ask now are building blocks for bigger ideas in high school and beyond. Scientists use the same skill of asking testable questions when they study electromagnetism (the combined study of electric and magnetic forces). Here is how the concepts you are learning now connect to what comes next.

What You Learn Now (Middle School)	What Comes Next (High School & Beyond)
Electric force depends on distance and charge amount	Coulomb's Law gives an exact equation: F = k × q₁ × q₂ ÷ d²
Magnetic force depends on distance and magnet strength	Magnetic field equations describe exact relationships
Electricity and magnetism are related	Maxwell's equations unify them into one theory of electromagnetism
Ask investigable questions about force factors	Design full experiments, model with math, and publish findings

How middle school concepts connect to advanced physics

The crosscutting concept of Scale, Proportion, and Quantity becomes very important later. Right now, you are learning that force changes with distance. In high school, you will learn exactly how much it changes—force decreases with the square of the distance. That means doubling the distance makes the force four times weaker!

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Fun Fact

Every time you use a phone, you are using electromagnetism. The touchscreen uses electric fields. The speaker uses a tiny electromagnet. Scientists figured all of this out by asking investigable questions, just like the ones you are learning to write!

SECTION 9

Practice Problems

Question 1: CONCEPTUAL

Which of the following is an investigable question about magnetic force? A) Why are magnets so cool? B) How does the number of wire coils on an electromagnet affect the number of paper clips it can pick up? C) What is the best magnet in the world? D) Will magnets work on Mars?

Show answer

B is correct. It names a specific independent variable (number of wire coils) and a measurable dependent variable (number of paper clips). A is wrong because "cool" is an opinion, not something you can measure. C is wrong because "best" is also an opinion—best at what? D is interesting but too vague to test in a classroom; it does not specify what variable to change.

Question 2: BASIC

A student asks: "How does distance affect the strength of the electric force between two charged balloons?" Identify the independent variable, dependent variable, and one controlled variable. A) Independent: balloon color; Dependent: force; Controlled: distance B) Independent: distance; Dependent: force strength; Controlled: amount of charge on each balloon C) Independent: force strength; Dependent: distance; Controlled: balloon color D) Independent: amount of charge; Dependent: distance; Controlled: force strength

Show answer

B is correct. The student changes distance (independent), measures force strength (dependent), and should keep charge the same (controlled). A is wrong because balloon color is not mentioned in the question and does not affect force. C is wrong because it has the independent and dependent variables switched—you change distance, not force. D is wrong because the question asks about distance as the factor being changed, not charge.

Question 3: INTERMEDIATE

A student observes that a magnet picks up 12 paper clips when touching them, but only 3 paper clips from 2 cm away. She wants to investigate this pattern further. Which question would BEST help her explore the cause-and-effect relationship she observed? A) Why do magnets lose their strength over time? B) How does the distance between a magnet and paper clips affect the number of paper clips the magnet can hold? C) What makes some metals magnetic and others not? D) Is the magnetic force stronger than gravity?

Show answer

B is correct. It directly connects to her observation (distance changed the number of clips), names a clear independent variable (distance), and names a measurable dependent variable (number of paper clips). A is wrong because her observation was about distance, not time or magnets losing strength. C is an interesting question but asks about a different topic (material properties, not force strength vs. distance). D is wrong because it compares two forces without naming a specific variable to change or measure.

Question 4: APPLIED

A team of students is designing an electromagnet for a school engineering challenge. They want their electromagnet to be as strong as possible. They have a battery, a nail, and copper wire. They can change the number of wire coils and the type of nail (iron vs. steel). Which pair of investigable questions would help them the most? A) "Why is iron magnetic?" and "What is electricity?" B) "How does the number of wire coils affect the electromagnet's strength?" and "How does using iron vs. steel for the core affect the electromagnet's strength?" C) "What is the strongest electromagnet ever built?" and "How much does a paper clip weigh?" D) "Do electromagnets work underwater?" and "Is copper the best wire?"

Show answer

B is correct. Both questions name specific variables the students can actually change (number of coils, type of nail material) and a measurable outcome (electromagnet strength, which can be measured by how many paper clips it picks up). These questions directly help them design a better electromagnet. A is wrong because both questions are background knowledge questions, not investigable with a simple experiment. C is wrong because "strongest ever built" requires research, not an experiment, and paper clip weight does not relate to electromagnet design. D has some potential but "best wire" is vague (best at what?) and underwater testing does not help them make it stronger.

Question 5: CRITICAL THINKING

Two students are arguing. Student A says: "Electric force and magnetic force are basically the same thing because they both get weaker with distance." Student B says: "They are completely different forces with nothing in common." Use what you know about investigable questions and force factors to evaluate both claims. Which statement is most accurate? A) Student A is correct—they are the same force. B) Student B is correct—they have absolutely nothing in common. C) Both students are partly wrong. The forces share some patterns (like getting weaker with distance) but have different causes, so they are related but not identical. D) Neither student can be evaluated because we cannot test these claims.

Show answer

C is correct. Electric and magnetic forces do share patterns—both are non-contact forces that get weaker with distance and can attract or repel. However, they have different causes (charges vs. poles/moving charges) and affect different materials. Student A is too extreme because sharing one pattern does not make them the same. Student B is too extreme because they clearly share several features. A is wrong because having similar patterns does not make them identical—a cat and a dog both have four legs, but they are not the same animal. B is wrong because the comparison table in this lesson shows many shared features. D is wrong because you CAN design investigable questions to test specific claims about each force and compare their behaviors.

SUMMARY

Lesson Summary

Summary

In this lesson, you learned that electric forces and magnetic forces are both non-contact forces that can attract or repel. The key factors that influence their strength include distance between objects, amount of charge, magnet strength, and number of wire coils in an electromagnet. Both forces get weaker as distance increases, which is a pattern that connects to the crosscutting concept of Cause and Effect.

An investigable question names a specific independent variable (what you change) and a dependent variable (what you measure). It avoids opinions, vague language, and questions that cannot be tested with available tools. The NGSS Science and Engineering Practice of Asking Questions is the foundation of all scientific investigation. Use the question frame—"How does [factor] affect [force strength]?"—and you will be thinking like a real scientist.