Materials
- Hollow Solenoid
- Strong Bar Magnet
- Flash Bulb(s) from a Camera
- 2 Alligator Clip Wires
Procedure
- Separate the flash bulbs from the pack without removing the two metal leads into the bulb
- Connect one end of the flash bulb to one end of the solenoid using the alligator clip
- Connect the other end of the flash bulb to the other end of the solenoid using the other alligator clip
- Thrust the bar magnet into the center of the solenoid and remove quickly
- The bulb go out with a loud pop and a bright flash
Explanation
As the magnet is placed into and pulled out of the solenoid a current is produced. This is because changing magnetic flux (how strong the magnet is) produces a potential difference in the wire. A potential difference causes a current to flow. If the current is large enough, the flash bulb will go off. If for some reason the flash bulb does not go off, try to pull the bar magnet out of the solenoid with more force, or try using a stronger magnet.
Reinforcement Activities
Use a Tangent Galvanometer to measure the strength of Earth’s magnetic field by producing a current in a coil of wire and measuring that current.
Have students investigate how the shape of a conductor affects the magnetic field patterns. The Electromagnetic Field Experiment can be used individually by students or can be used by the teacher on an overhead. Three different shaped conductors are arranged in a plastic base and students can investigate the magnetic flux patterns using iron filings and tiny compasses.
Light a light bulb without a battery and keep it lit instead of just a flash by using a Ring Thrower. This powerful apparatus can throw a metal ring 12 feet in the air. To light a light bulb, just take a coil of insulated wire and connect a light bulb to each end of the coil. Then turn the ring thrower on and place the coils of wire over the top of the ring thrower. The ring thrower will buzz and the light bulb will light. The light can even be made brighter by wrapping more coils of wire around the top of the ring thrower.
