## PPP: Building an Electromagnetic Junkyard Crane **Driving Question:** "How do real junkyard cranes use electromagnets to sort and move scrap metal, and can I build a working scale model that demonstrates the same physics?" **The story:** Junkyard cranes are one of the biggest real-world uses of electromagnets. They pick up entire cars using nothing but electricity and coiled wire. What makes them special is the switch: turn the current on, the crane grabs a car. Turn it off, the car drops exactly where you want it. You can't do that with a permanent magnet. This project builds a working scale model of one and tests the physics behind it. **Your website:** itsdanielsultan.github.io/Physics-Website/ tracks the full process from brainstorming to final build. **Connection to your passions (from Post 1):** This falls under your "Building Projects and Problem Solving" passion. You wrote that starting with nothing and creating something that works is deeply satisfying. That's exactly what this is: taking wire, a nail, some wood, and a battery and turning them into a machine that lifts metal.
## Shopping List (Dollarama + Dollar Tree + Walmart) Go first thing in the morning or send someone. Everything is under $15. | Item | Where | Cost | | --- | --- | --- | | Popsicle sticks (for the crane frame) | Dollarama craft section | $2 | | Hot glue gun + sticks (or strong tape) | Dollarama | $4 | | Large iron bolt or nail (3-4 inches) | Hardware aisle or toolbox at home | $0-2 | | 22-gauge copper wire (3-5 metres) | Walmart electrical aisle, or strip old cables | $3-5 | | 9V battery | Dollarama electronics | $2 | | Push button switch or toggle switch | Dollarama electronics section, or use a clothespin + foil as a DIY switch | $0-2 | | String or fishing line | Around the house or Dollarama | $0-2 | | Paperclips, screws, washers, small bolts | Around the house or Dollarama hardware | $0-2 | | Bristol board (for trifold) | Dollarama or Walmart | $2-3 | | Markers (red, blue, black at minimum) | At home or Dollarama | $0-2 | **Also check your house for:** old phone charger cables (copper wire inside), nails/bolts in the toolbox, batteries from remotes, string/yarn
## How to Build the Crane (1-2 hours) ### This is a DEVICE, not a demo. It has 3 systems that work together. ### System 1: The Rotating Base 1. Cut a square base from thick cardboard or use a cutting board (about 20x20 cm) 2. Cut a second smaller square (about 15x15 cm). This is the turntable. 3. Put a bolt or nail through the center of both squares (small on top, large on bottom). Add a washer between them. The top square should spin freely on the bolt. That's your rotating platform. 4. The crane arm sits on the turntable. You can grab the base with one hand and spin the top platform to rotate the crane. ### System 2: The Boom Arm + Crank Lift 1. Build a vertical tower: use 2 wooden rulers or thick dowels, standing upright on the turntable. Glue or tape them firmly. About 25-30 cm tall. 2. Build a horizontal boom: attach another ruler or dowel to the top of the tower, sticking out sideways (like a T or L shape). Reinforce with hot glue or tape. The boom should be 15-20 cm long. 3. **The crank:** Take a thick marker or small wooden dowel. Wrap string around it like a spool. Mount it horizontally near the top of the tower (tape it so it can still rotate when you turn it). One end of the string goes over the boom tip and down to the electromagnet. When you turn the marker/dowel, string wraps around it and the electromagnet rises. Turn it the other way, the electromagnet lowers. This is your lifting mechanism. 4. **Why this matters:** A hand crank is a real mechanical system. It converts rotational motion into linear motion. It uses torque. That's physics. ### System 3: The Switchable Electromagnet 1. Wrap 50+ turns of copper wire tightly around the iron bolt. 2. Wire one end to the 9V battery positive terminal. 3. Wire the other end through a push button switch, then to the battery negative terminal. 4. Tie the bolt to the string from the crank so it hangs from the boom tip. 5. Run the wires along the boom and down the tower to the battery and switch on the base. ### How it all works together - Rotate the base to position the crane over an object - Lower the electromagnet using the crank - Press the switch to turn on the magnet. Object sticks. - Raise the electromagnet using the crank (object comes up with it) - Rotate the base to a new position - Release the switch. Object drops. - That's a fully functional electromagnetic crane. Three systems: rotation, lifting, and magnetism.
## The Experiment (20 min) Now test it like a scientist. Three experiments: ### Test 1: How do coil turns affect lifting capacity? Unwrap to 20 turns. Count max paperclips it lifts. Then 30, 40, 50, 60 turns. | Turns | Paperclips Lifted | | --- | --- | | 20 | | | 30 | | | 40 | | | 50 | | | 60 | | ### Test 2: What's the heaviest object it can lift at 50 turns? Try: paperclip, screw, washer, small bolt, key, spoon. Record which ones it holds and which ones fall. | Object | Weight (estimate) | Lifted? | | --- | --- | --- | | Paperclip | ~1g | | | Screw | ~5g | | | Washer | ~8g | | | Small bolt | ~15g | | | Key | ~20g | | ### Test 3: Does the crane drop objects instantly when power is cut? Time how fast objects fall after you release the switch. Note: some residual magnetism may remain in the nail. That's called "magnetic remanence" and it's a real physics concept.
## The Physics (for trifold and website) **Solenoid equation:** B = u0 x n x I - More turns = stronger field = lifts more weight **Energy transformation chain:** Electrical energy (battery) -> Magnetic field energy (electromagnet) -> Mechanical energy (lifting objects against gravity) **Work done by the crane:** W = F x d = mg x h (lifting an object of mass m through height h) **Why the switch matters:** Unlike a permanent magnet, an electromagnet can be turned on and off. This is why real cranes, MRI machines, and maglev trains use electromagnets, not permanent magnets. Controllability is the key advantage. **Magnetic remanence:** After you turn off the power, the iron core may stay slightly magnetized. This is because some of the magnetic domains in the iron don't fully randomize. In industrial applications, this is sometimes a problem (objects stick when they shouldn't) and engineers use AC demagnetization to fix it. **Connection to other units:** - Unit 1 (Dynamics): The crane lifts objects against gravity (F = mg) - Unit 2 (Energy): Work and energy conservation in the lifting process - Unit 3 (Fields): Magnetic field of a solenoid, Faraday's Law - Unit 4 (Waves): Electromagnetic radiation is produced by accelerating charges in the coil
## Trifold Layout ### Left Panel: THE BUILD **Title:** "Electromagnetic Crane" **Your name, course, teacher** **Driving question** **3 Systems Diagram:** Draw the crane and label all 3 systems: 1. Rotating base (turntable on a bolt pivot) 2. Crank lift (spool + string + boom arm, converts rotation to linear motion) 3. Switchable electromagnet (solenoid on iron bolt, controlled by push button) **Circuit diagram:** Battery -> switch -> coil around bolt. Label everything. **Photos of the build process** (before and after) ### Middle Panel: THE PHYSICS + DATA **Solenoid equation** written big: B = u0 x n x I **Energy transformation diagram:** Chemical (battery) -> Electrical (current) -> Magnetic (solenoid field) -> Mechanical (lifting against gravity) **Torque in the crank:** T = F x r (turning the crank handle at radius r to lift weight F) **Work done lifting:** W = mgh (mass of object x gravity x height lifted) **Data tables** from all 3 tests **Graph:** Plot turns vs paperclips lifted (should curve upward) **Photo:** The crane picking up paperclips (action shot) ### Right Panel: ANALYSIS + APPLICATIONS **Results summary:** Did more turns lift more? What was the heaviest object? **Sources of error:** Battery draining, uneven coil wrapping, magnetic remanence **Real-world applications with photos:** - Junkyard cranes (picking up cars) - MRI machines (medical imaging) - Maglev trains (levitation) - Electric motors (every car, fan, washing machine) **Conclusion**
## Website Posts (add to itsdanielsultan.github.io/Physics-Website/) ### Post 1: DONE (already live) ### Post 2: Driving Questions "After brainstorming, I kept coming back to my interest in building things and how machines work. I started thinking about electromagnets after we covered magnetic fields in class. My first question was broad: 'How do electromagnets work?' I refined it by looking at real applications. Junkyard cranes stood out because they're one of the biggest and most visible uses of electromagnets in daily life. They can pick up entire cars and drop them on command, something a permanent magnet can't do. My final driving question: How do real junkyard cranes use electromagnets to sort and move scrap metal, and can I build a working scale model that demonstrates the same physics? I used AI to help tighten the wording so the question was testable and specific." ### Post 3: Research "Junkyard cranes (also called electromagnetic lifting magnets) have been used in scrap metal yards since the early 1900s. They work by passing current through a coil of wire wound around an iron core, creating a strong magnetic field (B = u0 x n x I). The iron core amplifies the field because its magnetic domains align with the external field. The key advantage over permanent magnets is controllability: operators can pick up ferromagnetic metals (steel, iron) and release them at a precise location just by flipping a switch. Modern junkyard cranes operate at high voltages and can lift thousands of kilograms. They're also used in recycling facilities to separate ferrous metals from non-ferrous materials like aluminum and plastic. The same physics applies to MRI machines, maglev trains, and electric motors. Sources: SPH4U textbook (Magnetic Fields chapter), HyperPhysics, IEEE Spectrum article on electromagnetic material handling, Eriez Manufacturing (industrial magnet company)." ### Post 4: Plan of Action "Week 1: Research electromagnets and crane design. Week 2: Buy materials, build the crane structure and electromagnet, wire the switch circuit. Week 3: Run experiments (coil turns vs lifting capacity, max weight test, drop speed test), build trifold, prepare presentation." ### Post 5: Proof Upload: photos of the build process, the finished crane, the crane lifting objects, your data tables ### Post 6: Conclusion "I built a functional electromagnetic crane that picks up and drops metallic objects using a switchable electromagnet. Testing showed that increasing coil turns from 20 to 60 increased lifting capacity roughly linearly, matching B = u0nI. The crane could lift objects up to [X] grams. Magnetic remanence caused a slight delay in dropping objects after power was cut. This project demonstrated how the same electromagnetic principles from class are used in junkyard cranes, MRI machines, and maglev trains."
## Presentation Script (2-3 min) "Hi, I'm Daniel. I built an electromagnetic crane that picks up and drops metallic objects with a switch. The core of the project is a solenoid, a coil of copper wire wrapped around an iron bolt, mounted on a popsicle-stick crane frame. When I press the switch, current from a 9-volt battery flows through the coil, creating a magnetic field that magnetizes the iron core. The bolt becomes an electromagnet and grabs nearby metal objects. When I release the switch, the current stops, the field collapses, and the objects drop. I ran three experiments. First, I tested how the number of coil turns affects lifting strength. Going from 20 to 60 turns, the number of paperclips lifted increased roughly linearly, which matches the solenoid equation B equals mu-naught times n times I. Second, I tested the heaviest object the crane could hold at 50 turns. Third, I checked whether objects drop instantly when power is cut, and found a slight delay caused by magnetic remanence, which is residual magnetism left in the iron core. The physics here connects to all four units in the course: dynamics in the lifting force, energy conservation in the work done against gravity, magnetic fields in the solenoid, and even electromagnetic waves produced by the current. The same principles power junkyard cranes, electric motors, MRI machines, and maglev trains. Thank you."
## Checklist - [ ] Get materials (check house, then store in the morning) - [ ] Build the electromagnet (15 min) - [ ] Build the crane structure (30-45 min) - [ ] Wire the switch (5 min) - [ ] Run all 3 experiments and fill in data (20 min) - [ ] Take photos of everything (setup, action shots, data) - [ ] Build the trifold (45 min) - [ ] Add posts 2-6 to your website (30 min) - [ ] Submit on Google Classroom: website link + trifold photo + crane photo - [ ] Practice presentation twice **Total: about 3 hours of solid work**