Remember the experiment on how to make an electromagnet? When electric current flows through a wire coiled around an iron nail, it attracts the paper clips and thumbtacks, right? This time, let’s do a twist on that experiment. This one is called the magnetic suction experiment and you’ll be amazed with how this principle of electromagnetism works on some devices that we use everyday – like doorbells.
The Experiment
Let’s begin by listing the materials needed. Here they are.
a) 12 meter of insulated bell wire
b) 10 to 15 cm long and 6 mm in diameter plastic or cardboard tube
c) 6 volts (or more) large battery
d) largest iron nail that will fit loosely inside the tube
e) wire stripper and alligator clips ( to attach and secure the wire on the battery)
Materials and Setup Requirement
Actual Experiment Photo
Image Sources: Exploratorium Website
Let’s now proceed with the step by step process. Here we go.
- Hold the tube and tightly wrap as many coils of wire as possible around it.
- Strip off both ends of the wire and connect each end to each battery terminal using alligator clips (or tape as alternative).
- Insert the nail in the coiled wire (in a vertical position) and allow the electric current to flow.
- Try to switch on and off the electric current for about 3-5 seconds.
- Reverse the battery terminals and do the same process.
We observed that when the power is on, the nail is being sucked into the coil. What you just saw is the principle of magnetic suction at work. We know that this setup, based also on the previous experiment, creates a magnetic field that attracts magnetic objects like paper clips and thumbtacks. In this experiment, it was the iron nail which the coil used to attract.
Principle and Application
When electric current passes through the coil of wire, a magnetic field is created. The iron atoms (of bell wires) are loops of moving charges that act like small magnets pointing in different directions. Since magnets have north and south poles, a nail made of iron that is brought near them will be magnetized. Based on the principle of electromagnetism, opposite poles attract each other. In this experiment, the south pole of the nail is attracted by the north pole of the coil. When the direction of electric current is reversed, the poles of the electromagnet are also reversed and the nail is again sucked by the coil.
Doorbells, pinball machines, and starter switches of our cars are devices that operate under the principle of magnetic suction. Once electric current is induced in the coil, a rod in these devices is activated, triggering them to operate.
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