# All Science Fair Projects

## Electromagnets and the number of coils

### Materials

The materials required for this science project:
- an electric screw driver
- 4 magnets
- 1 roll of masking tape
- 3 hollow boxes of the same size.
- 1 spool of insulated wire (PVC insulated or varnish insulated)
- Paper cutter
- 2 crocodile clips
- a digital voltmeter
- a pair of scissors

### Procedure

1. For this science project, the independent variable is the number of turns in the coil. The dependent variable is the amount of voltage induced in the coils by the rotating magnet. This is measured by using the digital voltmeter. The constants (control variables) are the speed of the rotating magnets, the strength of the magnets, the size of the copper wire and the size of the box.

2. Using the masking tape, the four magnets are fixed to the shaft of the electric screw driver as shown in figure 1 above.

3. A hole is cut out of the carton box as shown in figure 1. The hole should be large enough to insert the 4 magnets, attached to the shaft of the screw driver, inside the box while holding the handle of the screw driver on the outside.

4. The copper wire is wound around each of the three boxes. The first box is wound with 150 turns, the second box with 300 turns and the third box with 450 turns.

5. Approximately 2 cm of the insulation at the tip of the wires are removed using the paper cutter.

6. The first box with 150 turns is selected first. The ends of the wires are fixed to the digital AC voltmeter using the crocodile clips. The magnets that are attached to the electric screw driver are inserted into the hole in the box. The screw driver is turned on and it will start to spin inside the box. The voltage measured on the digital AC meter is recorded in the table given below.

7. Procedure 6 is repeated using the boxes with 300 turns and 450 turns.

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Complexity level:
8
Project cost (\$):
70
Time required:
1 day to prepare, 1 day for experiment
Material availability:
The wires can be purchased at a hardware shop.
Safety concerns:

Basic safety requirements