Practical worksheet 3

Discussion:

1. The more turns of wire your magnet has, the better. Keep in mind that the further the wire is from the core, the less effective it will be.

The more current that passes through the wire, the better. Caution! Too much current can be dangerous!  Why?

Possible Ans: As electricity passes through a wire, some of the electrical energy is converted to heat. The more current that flows through a wire, the more heat is generated. If  double the current passing through a wire, the heat generated will increase 4 times! If triple the current passing through a wire, the heat generated will increase 9 times! Things can quickly become too hot to handle.

2. Why is it (in detail) that the more coils you add to an electromagnet, the stronger its magnetic field is?

Possible Ans: Depending on the thickness of the wire, might be able to get a meter of wire wrapped in a single layer along a core only a few centimeters long. With each turn, you add the magnetic force. And we are coiling it such that the lines of magnetic force are parallel and pointing in the same direction. We can add more coils on top of the first row, and this just adds more field strength. In technical terms, every coil of wire increases the "magnetic flux density" (strength) of magnet. The magnetic field on the outside of the coil resembles a bar magnet. The right hand rule can be applied to determine the North pole: if to hold the coil in your right hand, and the current flow is in the direction our fingers are pointing, the North pole is the end where your thumb is.

3. Try experimenting with different cores. Explain.  

 Possible Ans: A thicker core might make a more powerful magnet. Just make certain that the material you choose can be magnetized. 

4. Student can test  core with a permanent magnet.  Explain.  

Possible Ans: If a permanent magnet is not attracted to core, it will not make a good electromagnet. An aluminum bar, for example, is not a good choice for your magnet's core.