To investiagate how the magnetic flux density B at the centre of a flat coil is directly proportional to the number of turns in the coil.
Diag: Power supply , ammeter , coil , variable resistor in series.
Procedure:
1. Make a coil of N turns using a cylinder of radius r. Connect the circuit as shown.
2. Record the number of turns N. Adjust the variale resistor and note the current I.
3. Using a Hall probe connected to a data logger and computer , record the reading of magnetic flux density B .Ensure the hall probe is placed at the centre of coil.
4. Repeat steps 1 to 3 by varying N, keeping I constant to obtain 6 sets of readings of N and B.
5 Plot a graph of B vs N. A graph of B against N would be linear
Control of variables :
The radius of the coil is constant when N is varied
The current is kept constant by adjusting the variable resistor when N is varied.The ammeter reading should remain constant .
Reliabiltiy :
1. The Hall probe must be placed at the same location at the centre of the oil in the plane of the coil. It is also aligned perpendicular to the plane of the coil. Draw a diagram to shown this orientation.
2. The coil and probe should be kept away from other magnetic fields.
3. The Earth's magnetic field is negligible.
