Static Electricity

101 Phy Tricks
pg 52: Rub a plastic comb through your hair a number of times, or rub it hard with a piece of woollen fabric. Then hold the comb near some tiny scraps of tissue paper.

333 Tricks
pg 95: Charge comb and use it to make ping pong balls dance around

Light a fluorescent tube by rubbing it with a balloon?

Electric Current

101 Phy Tricks
pg 66: Wind a wire tightly around a nail. Use tape to hold the coil in place. Put as many turns around the nail as you can. Make a simple switch from thumbtacks and a paper clip and connect your coil to the switch and the battery. Complete the circuit with a wire from the other side of the switch to the battery and switch on. With the current flowing, dip the end of the nail into a pile of small nails, pins or paper clips. Lift your electromagnet clear and see how many you have picked up.

pg 62: Make a simple circuit with a bulb and battery. Carefully cut one of your wires, trapping its bare ends under thumbtacks pushed into a soft wood base. Also trap a paper clip or a strip of tin foil under one of the thumbtacks. When the paper clip or foil touches the other thumbtack, the circuit is completed and the bulb will shine.


Martin Gardner
pg 55: Mount a small light bulb on a board. Below it are three two-way push-button switches. Call them A, B, and C. You show by pushing switch A that it turns the bulb on and off. Punching the other two switches has no effect on the light. Challenge someone to locate the switch that operates the bulb. Naturally he pushes A, but the bulb stays dark. Allow him a second chance. He tries, say, C. Again the light remains off. Only B remains. It operates the light.

333 Tricks
pg 97: Build a battery.

Turning World Inside Out
M7: Make a small field coil and two supports in which to place the ends of the field coil. Make the field coil of the magnet by winding 10 turns of varnish-coated noninsulated number-22 wire. Make the ends of the wires that extend from the field coil into hook shapes, as shown in the illustration. Scrape the varnish off the top half of the two wire ends. Shape two paper clips into two rigid supports that have small loops at the top. With a strong rubber band, hold the two supports fixed against the two ends of the battery. Insert the hook shaped wires coming out of the field coil into the loops at the top of the two rigid supports, so that the field coil lies just above the disk-shaped magnet, which is placed atop the battery at its middle. Current flows through the field coil as long as its ends are in electrical contact with the supports.
N3: A bar magnet moved at the proper frequency in and out of a hanging coil of wire starts the coil swinging, showing that the direction of the induced EMF is given by Lens's law. Construction is on page N3.