Electric motors Activity 5
How an electric motor works • A coil of wire with a current produces a magnetic field. • The coil then acts like a small magnet. • When the coil is near a stronger magnet, the coil will move to align with the stronger magnet due to the force of the stronger magnet. • In a motor, the current in the coil switches direction over and over again, so the coil keeps spinning as it tries to align with the magnetic field. http://www.youtube.com/watch?v=ziWUmIUcR2k (build a simple motor) http://www.youtube.com/watch?v=Q2mShGuG4RY (how it works) http://www.youtube.com/watch?v=1W1sbFALXEA (how it works)
Extending the discussion to sea perch • This simple motor is related to the motors that you will attach to your SeaPerch ROV. • If you opened a motor up, you would find coils of wire and magnets. • When the wires are connected to a power supply, the motors will spin.
Extension activity • Take the motor you have built and turn the battery around • The current will run in the opposite direction through the loops of wire. • What happens to the direction in which the loop spins? • At times, you’ll want to put your SeaPerch in reverse – in next week’s activity, we’ll learn how to build a circuit where you can change the direction of the current.
more cool extensions • Building a speaker out of paper cups, wires, and magnets: • http://cse.ssl.berkeley.edu/lessons/indiv/regan/speakerlab.html • http://www.exploratorium.edu/afterschool/activities/docs/cupspeaker.pdf • Explore the relationship between electric fields and magnetic fields. • Place a compass close to the wire. Connect the wire to a power supply and see that the compass needle is deflected. Change the position of the compass. Notice it is deflected in a different direction. • http://www.youtube.com/watch?v=BM4m2GId3F8&feature=fvst (Oersted’s Discovery)
Source of Activity • http://www.phillyseaperch.org/learning-modules.html