1. Magnetic Fields – Learning Outcomes  Demonstrate the magnetic fields in a magnet, long straight wire, loop, and solenoid.  Describe these fields with particular emphasis on the vector nature of magnetic fields.  Discuss Earth’s magnetic field and its use in navigation. 1

2. Magnetic Fields  A magnetic field is any region of space where magnetic forces can be felt. The direction of the magnetic field at a point is the direction of the force on a north pole if it were placed at that point.  A magnetic field line is a line drawn in a magnetic field so that the tangent to it at any point shows the direction of the magnetic field at that point.  The closer together magnetic field lines are, the stronger the magnetic field. 2

3. Magnetic Field Around a Magnet 3 by Mpfiz – public domain

4. Right-Hand Rule  The right-hand rule states that if the right hand clasps a conductor with the thumb pointing in the direction of the current, the fingers give the direction of the magnetic field around the conductor. 4 by jfmelero – CC-BY-SA-4.0

5. Magnetic Field Around a Wire 5 by victor blacus – CC-BY-SA-3.0

6. Magnetic Field Around a Loop 6

7. Magnetic Field Around a Solenoid 7 by unknown artist – public domain

8. To Demonstrate the Magnetic Field around A Wire / Loop / Coil / Solenoid 1.Create a level surface perpendicular to the wire. 2.Using a power supply, send a current (~2A) through the wire. 3.Place a plotting compass near the wire and mark both ends of the needle on the surface. 4.Move the compass so that its south pole is at the dot that marked the previous north pole and mark the new north pole. 5.Repeat #4 to plot a curve around the wire and repeat #3 and #4 to plot multiple curves. Use arrowheads to show the direction of the field. 8

9. The Earth  The Earth has a magnetic field, generated by electric currents in its molten iron core.  While not a perfect analogy, we can pretend the Earth has a bar magnet in its centre, with the south pole of the magnet pointing northish, and the north pole of the magnet pointing southish. 9 by zureks – edited under public domain