HAND CRANK GENERATORS OVERVIEW & PURPOSE Energy is neither created nor destroyed, but converted from one form to another. The majority of our electricity (how we power our homes, schools, etc.) comes from generators that convert mechanical energy into electrical energy. In this experiment, students learn that it takes spinning a generator (mechanical energy) to create the electricity (electrical energy) to power a light bulb. There are a limited number of methods to generate electricity: 1) Static electricity, 2) Electromagnetic induction (turning a generator), 3) Photo-electric effect (solar panels), 4) Nuclear transformation (decay releases charged particles), 5) Thermo-electric effect, and 6) the Piezo-electric effect. The majority of our electricity comes from generators (electromagnetic induction). A generator converts mechanical force into electrical current. Inside a generator we have coiled wire (usually copper) and magnets. When we spin the wire near a magnet, we can induce the flow of electrons in the wire. This flow of electrons is electricity. MATERIALS ❏ Antique hand-crank generator ❏ Plastic hand-crank generators ❏ Alligator clips ❏ Socket base for light bulbs ❏ various light bulbs (incandescent, LED, CFL) ❏ PROCEDURE With the old-fashioned hand-crank generator: rdcep.org/demos
page 1 1. Connect the generator to the light bulb stand using the red and black alligator clips. 2. Screw in 1 of the 3 light bulbs (low wattage incandescent, LED, or fluorescent). 3. Turn the handle to power the light bulb. a. How much work does it take to light the various types and wattages of bulbs? With the modern plastic generators: 1. Use alligator clips to connect two generators. 2. Turn the crank of one generator and watch what happens to the second generator’s crank. POST-LAB QUESTIONS 1. What happens when you stop turning a generator? 2. What is the role of switches in your home? 3. Are you creating energy from scratch? (What are you converting into electricity?) 4. What happens to the speed of the second generator? (efficiency) 5. What is the reverse of a generator? Give an example. rdcep.org/demos
page 2