Make a wire spring jump up and down with electro-magnetism
Suitable For
Grade 8
Difficulty
3
Time Required
<2 Days
Supervision
Advised
What’s it about?
In this science experiment, you will use the power of electric current to make a thin wire coil behave in a mysterious way. When current is passed along a conductor, the conductor behaves like a magnet, especially if the conductor or wire is formed in a coil. A wire twisted along the base of another object to form a coil, is called an electro-magnet:
Topics covered
Magnetism, Electromagnet, Supersaturated, Electrolyte
What will I need?
- 9-VOLT BATTERY
- THIN COPPER WIRE & INSULATED WIRE
- STYROFOAM BALL
- SMALL, FLAT BALL
- SALT
- PENCIL
- BOOKS
Procedure (Method)
In this science experiment, you will use the power of electric current to make a thin wire coil behave in a mysterious way. When current is passed along a conductor, the conductor behaves like a magnet, especially if the conductor or wire is formed in a coil. A wire twisted along the base of another object to form a coil, is called an electro-magnet:
- Twist a thin copper wire around the base of a pencil to form a coil and slip it off the pencil.
- Push a copper nail through the centre of a Styrofoam ball so the both ends stick out about 10-20mm. Tie the one end of the thin copper wire to the head of the copper nail.
- Push the sharp end of a long pencil in the side of the Styrofoam ball so that it is perpendicular to the nail.
- Fix the other end of the pencil in position on a stack of books so that the thin copper wire coil is suspended from the nail in the Styrofoam ball, about 100-150mm away from the books.
- Stretch out the wire coil suspended from the nail in the ball so that it becomes a kind of a ‘spring’ with the other end suspended just above the surface of the table.
- Fill a small, flat bowl with supersaturated warm salt water, and place it underneath the coil so that the bottom tip of the coil is just below the surface of the salt water.
- Ask your parents or an adult to help you strip away about 20mm of insulation of the ends of two insulated wires of about 400mm in length each.
- Connect the end of each of the insulated wires to the terminals of a 9-volt battery and connect one of the free ends of the insulated wire to the nail sticking out at the top of the Styrofoam ball.
- Now, place the other free end of insulated wire into the salt water solution in the bowl and see how the copper spring bounces on the water frantically!
How does it work?
The above experiment works because when electric current flows through an object like a thin copper wire coil, it creates a magnetic field around the object. The saltwater acts as an ‘electrolyte’ and hence a complete electrical circuit is formed between the battery, wires, nail and the copper coil spring, when the end of the insulated wire is placed in the salt water solution. The electrical current flowing through the spring turns it into an electro-magnet with a north and south pole, and pulls the ‘spring’ together.
When the spring is pulled together, the bottom end is pulled out of the salt-water or ‘electrolyte’, breaking the circuit and stopping the flow of current as well as the magnetic properties of the coil. As this happens, the ‘spring’ releases and the bottom end dips into the salt-water again. This process forms a continuous loop that will cause the wire to bounce up and down without end, until the insulated wire is removed from the salt water.
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