1. Week 9 Presentation 1 Electromagnets 1

2. Learning Objectives: 1. Determine the magnitude and direction of the magnetic field strength generated by a straight wire carrying current, a coil and a solenoid. 2. Determine the force applied to a wire Starter: What is an electromagnet ? 2

3. Calculating Magnetic Field Strength for a wire http://hyperphysics.phy- astr.gsu.edu/hbase/magnetic/magcur.html http://hyperphysics.phy- astr.gsu.edu/hbase/magnetic/magcur.html B = Magnetic field strength /T μ 0 = Magnetic permeability of free space r = radial distance / m 3

4. Calculating Magnetic Field Strength for a coil B = Magnetic field strength /T μ 0 = Magnetic permeability of free space R = Loop radius/ m 4

5. Calculating Magnetic Field Strength for a solenoid B = Magnetic field strength /T μ 0 = Magnetic permeability of free space N = Number of turns l = length of solenoid / m 5

6. Force on a Current-Carrying Conductor https://www.youtube.com/watch?v=tbCXaER0w-s 6

7. Right Hand Rule for Force I Direction of the current is conventional current (i.e. flow of positive charge) 7

8. Calculating Force on a Current- Carrying Conductor F = I L B F = I L B sinθ 8

9. Interactive activity http://www.trunity.net/iat- physics/view/game/53dfa7e00cf29d736ab6fcb c/?topic=54009e6c0cf2fd88643f16e3 9