Thursday, December 17, 2009

Energy Labs: Battery-Powered Experiments

Continuing on with the description of the labs we did in conjunction with the PBS NOVA video Einstein's Big Idea, here are our adaptations of the directions for two activities using batteries:

Make An Electromagnet

  • insulated copper wire
  • rubber band
  • "D" battery
  • 2 large nails
  • small paper clips
  • wire stripper (or scissors)

  1. Cut a piece of wire about 40 cm long.
  2. Use a wire stripper (or scissors, carefully) to remove about 1 cm of insulation from the ends of the wire.
  3. Using the center of the wire, coil the wire around one nail, leaving about the same amount of wire on either side.
  4. Wrap the rubber band around the ends of the battery to hold the the wire in place.
  5. Connect the wires to the battery to create an electromagnet. Try to pick up paper clips and the other nail. Only keep the battery connected to the wires for 30 seconds.
  6. Touch the head of the nail after the circuit has been connected for 30 seconds to feel how the electrical current is making the metal heat up.
Explanation: The point of this station is that the magnetic field can do work. It can lift objects as the energy of the field is transferred to the paper clips. Since the strength of the nail's magnetic field is proportional to the number of coils of wire around the nail, we also experimented with different lengths of wire and numbers of coils.

Electrical to Heat Energy

  • batteries (we used pre-made "battery packs" with 4 AAs held together with tape and rubber bands and connected + to - with wires)
  • small lightbulb (we used one from an electrical set which came with wires)
  • compass
  1. Connect the lightbulb to the batteries using the wires. 
  2. Leave it lit for 15 seconds and feel the bulb heat up. 
  3. Using the compass, see if you can detect the magnetic field generated by the electrical energy traveling through the wire.
Explanation: The light bulb demonstrates how electrical energy can be converted to light and heat energy. Most of the light bulb's energy is given off as heat. The electrical energy is also the result of a transformation, from chemical energy (in the battery). As we saw in the documentary, Michael Faraday, a self-taught scientist in 19th century England, was the first to propose that the compass was being affected by invisible lines of force flowing around the wire.