This laboratory investigates the factors that influence the intensity of a solenoid’s magnetic field. Participants will explore how the nature of the core, the current’s intensity, and the number of turns (coils) affect the magnetic field strength by observing the number of paperclips attracted to the solenoid. This hands-on activity demonstrates the principles of electromagnetism and provides an opportunity to manipulate and measure variables in an engaging way.
Educational Goals
- Visualize magnetic field lines: Learn how iron filings align with magnetic field lines, revealing the direction and shape of magnetic fields around different types of magnets.
- Understand magnetic pole interactions: Observe how like poles repel and opposite poles attract, gaining insights into the interactions between magnetic fields of multiple magnets.
- Interpret compass behavior in magnetic fields: Use a compass to study how its needle aligns with magnetic field lines, understanding the directional nature of magnetic forces.
- Develop laboratory skills: Practice setting up experiments, handling materials like iron filings, and documenting observations systematically.
- Analyze experimental results: Interpret patterns formed by the filings and compass orientations to understand the behavior of magnetic fields in various configurations.
- Connect theory with practice: Link classroom concepts about magnetism with real-world applications, enhancing comprehension of magnetic phenomena.
Protocol
Part A : The nature of the nucleus
- Connect the 600-turn solenoid to the power source using the connectors.
- Have more than 35 paper clips on the counter. Make sure to add paper clips between each experiment if some have fallen off the table.
- Place the soft iron core into the solenoid.
- Turn on the power source.
- Adjust the potential difference to 15 V.
- Touch the paper clips with the solenoid.
- Gently move the solenoid away from the paper clips and then remove the core.
- The approximate percentage of paper clips that are attracted by the solenoid is found in the results table.
- Repeat steps 1 to 8 with the five other types of cores and without a core (air core).
Part B : The current intensity
- Place the soft iron core into the solenoid.
- Adjust the potential difference of the source to 30 V.
- Touch the paperclips with the solenoid.
- Gently move the solenoid away from the paperclips and then remove the core.
- The approximate percentage of paper clips that are attracted by the solenoid is found in the results table.
- Decrease the potential to 15v. Place the soft iron core in the solenoid and touch the paper clips with the solenoid. Note the approximate number of paper clips that are attracted by the solenoid in the results table.
- Remove the core from the solenoid.
- Decrease the potential to 7v. Place the soft iron core into the solenoid and touch the paper clips with the solenoid. Note the approximate number of paper clips that are attracted by the solenoid in the results table. Remove the core from the solenoid.
- Disconnect the 600-turn solenoid from the current source, reattach the connectors to the terminals and place it on the table.
Part C : The density of turns
- Connect the 15-turn solenoid to the power source.
- Place the soft iron core into the solenoid.
- Adjust the potential difference to 15 V.
- Touch the paperclips with the solenoid.
- Gently move the solenoid away from the paperclips and then remove the core.
- The approximate percentage of paper clips that are attracted by the solenoid is found in the results table.
- Disconnect the 15-turn solenoid from the current source, reattach the connectors to the terminals and store it on the table.
- Repeat steps 1 to 7 with the 300-turn solenoid.
Anticipated Outcomes
Influence of the nature of the nucleus on the magnetic field strength of a 600-turn solenoid
| Nature of the nucleus | Approximate number of paper clips attracted to the solenoid |
| Soft iron | 40 |
| Glass | 0 |
| Wood | 0 |
| Aluminum | 0 |
| Copper | 0 |
| Nickel | 10 |
| Air | 0 |
Influence of current intensity on magnetic field strength of a 600-turn solenoid
| Amperage (A) | Approximate number of paper clips attracted to the solenoid |
| 4 | 100 |
| 2 | 50 |
| 1 | 25 |
Influence of the density of the turns on the magnetic field strength of a solenoid
| Number of turns | Approximate number of paper clips attracted to the solenoid |
| 15 | 2 |
| 300 | 20 |
| 600 | 40 |
The experiment aims to determine the factors that influence the intensity of the magnetic field produced by a solenoid. Three main variables are investigated:
- The core material (nature of the nucleus).
- The electric current intensity.
- The number of coil turns (spires).
Part A – Influence of the Core Material
Expected Outcome
The type of material inserted into the solenoid greatly affects the strength of the magnetic field. The solenoid attracts the most paperclips (about 40) when a soft iron (fer doux) core is used. Nickel, another ferromagnetic material, shows some effect (around 10 paperclips), while non-magnetic materials such as glass, wood, aluminum, copper, and even air (no core) attract none.
Scientific Reasoning
Ferromagnetic materials (like soft iron and nickel) become magnetized when placed inside a solenoid. This amplifies the magnetic field generated by the current. Materials without magnetic properties do not influence the field and, therefore, don’t attract objects like paperclips.
Part B – Influence of Electric Current Intensity
Expected Outcome
When the current is increased:
- At 1 A, the solenoid attracts around 25 paperclips.
- At 2 A, about 50 are attracted.
- At 4 A, up to 100 are attracted.
Scientific Reasoning
The magnetic field strength of a solenoid is directly proportional to the electric current flowing through it. As the current increases, more energy flows through the wire, generating a stronger magnetic field. This stronger field can attract more ferromagnetic objects (e.g., paperclips).
Part C – Influence of the Number of Turns (Spires)
Expected Outcome
Using the same current and core:
- The 15-turn solenoid attracts only 2 paperclips.
- The 300-turn solenoid attracts about 20.
- The 600-turn solenoid attracts around 40.
Scientific Reasoning
The magnetic field strength is also proportional to the number of turns of the wire in the solenoid. More coils mean more loops of wire contribute to the magnetic field, enhancing its intensity. Each loop adds to the total field, so increasing the number of turns makes the solenoid stronger.
Conclusions
From the three sections, we can conclude:
- Ferromagnetic cores like soft iron significantly increase magnetic strength.
- Higher current leads to a stronger magnetic field.
- More turns (spires) also result in a stronger field.
Practical Implications
Solenoids offer several advantages over permanent magnets:
- They can be switched on or off using electric current.
- The magnetic field strength can be controlled and varied by changing the current, the number of turns, or adding a core.
- This flexibility makes solenoids useful in devices like electromagnets, motors, relays, and MRI machines.
Significance and lessons learned
- Understanding electromagnetism
This lab provides a foundational understanding of how solenoids generate magnetic fields and the factors influencing their strength. - Practical applications
Solenoids are widely used in technology, including switches, motors, and magnetic locks. This lab demonstrates their functionality and versatility. - Hands-on experience
By manipulating core materials, current, and coil density, students gain practical skills in controlling and measuring magnetic fields. - Linking theory and practice
Students connect classroom concepts with real-world applications, reinforcing their understanding of magnetic fields and electromagnetism. - Encouraging scientific inquiry
This lab fosters curiosity and critical thinking by encouraging students to analyze how different factors impact magnetic field strength.
Summary of Assignment by Grade Range
Grades 6-8 (Middle School):
- Focus: Introduction to solenoids and basic observation of magnetic fields.
- Activities: Explore the effects of core material and current intensity on magnetic field strength.
- Learning Outcomes: Understand the concept of electromagnetism and its relationship with solenoids. Gain hands-on experience in assembling and observing solenoids.
Grades 9-10 (Junior High School):
- Focus: Intermediate exploration of multiple factors affecting solenoid performance.
- Activities: Investigate the influence of core material, current intensity, and coil density on the solenoid’s magnetic field.
- Learning Outcomes: Analyze patterns in experimental results and understand variable control. Develop practical skills in handling solenoids and power sources.
Grades 11-12 (High School):
- Focus: Advanced analysis of solenoid properties and practical applications of electromagnetism.
- Activities: Evaluate the impact of different variables and interpret their effects in relation to theoretical principles.
- Learning Outcomes: Master experimental techniques and result interpretation in electromagnetism. Connect findings to real-world applications like electric motors and magnetic devices.
Laboratory essentials
Instruments
- Solenoids
- One 15-turn solenoid
- One 300-turn solenoid
- One 600-turn solenoid
- Power source
- Connecting wires (2)
- Core materials (6)
- Soft iron
- Glass
- Wood
- Aluminum
- Nickel
- Copper
- Box of small paperclips