MS-PS2-3: What Makes Electric and Magnetic Forces Stronger
Also called NGSS MS-PS2-3 · Topic: Forces and Interactions · Physical Science
The Official Wording
Ask questions about data to determine the factors that affect the strength of electric and magnetic forces.
Clarification statement: Examples of devices that use electric and magnetic forces could include electromagnets, electric motors, or generators. Examples of data could include the effect of the number of turns of wire on the strength of an electromagnet, or the effect of increasing the number or strength of magnets on the speed of an electric motor.
Assessment boundary: Assessment about questions that require quantitative answers is limited to proportional reasoning and algebraic thinking.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What MS-PS2-3 Means in Plain English
Middle schoolers ask questions about data to find out what makes electric and magnetic forces stronger or weaker. They look at devices like electromagnets and motors and ask how coils of wire, current, distance or the number of magnets change the strength of the force.
Questions that need numbers stay within proportional reasoning and simple algebra, such as doubling the coils and comparing results. This builds on 3-PS2-3, where magnets and static charges act on each other, and leads to HS-PS2-5, which links electric currents to magnetic fields.
MS-PS2-3 I Can Statements
- I can ask a testable question about what changes magnetic strength.
- I can read data to find which factor makes an electromagnet stronger.
- I can explain how coils and current affect an electromagnet.
MS-PS2-3 Worked Example
An electromagnet made from an iron nail, a D-cell and insulated wire, with small steel washers as the measure.
Does wrapping more coils of wire around a nail make a stronger electromagnet?
Set It Up: A large iron nail, insulated copper wire, two D-cells in holders and a pile of small steel washers.
- Wrap 10 coils around the nail, connect one D-cell, and count the washers it lifts.10 coils: 2 washers
- Disconnect, rewind with 20 and then 30 coils, and test again.20 coils: 5 washers, 30 coils: 8 washers
- Repeat each count three times, unhooking the cell between tests so it stays cool.Counts within one washer
- Study the data and write a new question it raises.What if we add a second D-cell?
- Test that question with 20 coils and two cells in a row.Two cells: 9 washers
More coils lifted more washers, and a second cell made the same coil stronger still.
Why it works: Current in a wire makes a magnetic field, and more coils or more current add up to a stronger field around the iron core.
Common Mistakes with MS-PS2-3
Asking an untestable question
“Why is magnetism cool?”
Try this: Ask a question that names one factor and one measurement, like how the number of coils changes the number of washers lifted.
Changing coils and cells together
30 coils on two cells compared with 10 coils on one cell
Try this: Change one factor at a time. Keep the cell count fixed while testing coils, then test cells with the coils fixed.
Thinking all metals are magnetic
Testing aluminum foil and copper coins as the load
Try this: Magnets attract iron, steel, nickel and cobalt, not aluminum or copper, so use steel washers or clips to measure strength.
Where MS-PS2-3 Fits
Practice MS-PS2-3
Quick Check
- An electromagnet with 15 coils lifts 4 washers. What might happen with 30 coils?
- Name two ways to make an electromagnet stronger.
- What happens to an electromagnet when you disconnect the battery?