WARM-UP: 1. What metal is used to make ferromagnets? a. ironb. cobalt c. nickeld. All of the above This image (p. 517) shows a model of Earth as a large magnet. Use it to answer the questions that follow. 2. Which magnetic pole is closest to the geographic North Pole ? 3. Is the magnetic field of Earth stronger near the middle of Earth (in Mexico) or at the bottom of Earth (in Antarctica)? … Explain your answer.

ELECTROMAGNETISM CHAPTER 18 … SECTION 2 (VA SOL PS.11.ABC)

USING ELECTROMAGNETISM Two devices make electromagnetism more useful by strengthening the magnetic fields made by current-carrying wires:  Solenoids and Electromagnets (uses a solenoid to operate) Revisit/Recall the basics of Magnetism (from Friday):

SOLENOID (S Ō -L Ə - ˌ NID) definition: a coil of wire that produces a magnetic field when carrying an electric current magnetic fields around solenoids are similar to those of a bar magnet magnetic field strength of a solenoid increases as more loops are used and/or as the current in the wire is increased Magnetic Field Energy Source

TIME FOR A VIDEO RECAP / OVERVIEW… 1) Bill Nye: simple Solenoid & Electromagnetism: (copy/paste this link) 2) Magnets & Magnetism: (click on link)

ELECTROMAGNET definition: a coil that has a soft iron core and that acts as a magnet when an electric current is in the coil the solenoid’s magnetic field makes the domains inside the iron core line up the electromagnet’s magnetic field = the field of the solenoid + the field of the magnetized core … so the magnetic field of an electromagnet may be hundreds of times stronger than the magnetic field of just the solenoid itself To make it even stronger: increase the number of loops in the solenoid and/or increase the electric current in the wire

USES OF ELECTROMAGNETS : Electromagnets are useful because they can be turned on and off as needed (no current in the wire, the electromagnet is turned off) Scrapyard Cranes Doorbells 2-min video: no pics but very informative Galvanometer : used by electricians to measure current Mag-Lev Trains

{MORE} USES OF ELECTROMAGNETS : Generators (converts mechanical energy into electrical energy) Electrical Motors (converts electrical energy into mechanical energy)  All electric motors have an armature - a loop or coil of wire that can rotate  In electric motors that use direct current, a commutator (a ring split in half and connected to the ends of the armature) is attached to the armature to reverse the direction of the electric current. 0KiP34FMXiQSGVrYQC

EXIT TICKET Which of the following actions will decrease the strength of the magnetic field of an electromagnet? a. using fewer loops of wire per meter in the coilb. decreasing the current in the wire c. removing the iron cored. All of the above Look at the solenoids and electromagnets shown below. Identify which of them has the strongest magnetic field and which has the weakest magnetic field: a. b. c. d. The magnetic field of a solenoid can be increased by a. adding more loops per meter. b. increasing the current. c. putting an iron core inside the coil to make an electromagnet. d. All of the above An electric fan has an electric motor inside to change a. mechanical energy into electrical energy. b. thermal energy into electrical energy. c. electrical energy into thermal energy.d. electrical energy into mechanical energy.