Name:

Introducing Charges and Electricity

Experiment A: Balloon

Background information

The elementary principle behind electricity is that like charges repel, while opposite charges attract. A neutral object has no charge and is attracted to both positively and negatively charged objects.Positive charges have more protons; negative charges have more electrons.

When two materials are rubbed together like in the above diagram, this can create static electricity. When these charges move (ie. are not stationary or static) they are then called unbalanced charges.

Read through the following experimental procedure. Write down a hypothesis of what you think will happen at each step here:

Materials

  • 2 inflated balloons with string attached
  • Your hair
  • Aluminium can
  • Woolen fabric

Procedure

  1. Rub the 2 balloons one by one against the woolen fabric, then try moving the balloons together. Are they attracted to each other?
  2. Rub 1 of the balloons back and forth on your hair then slowly pull it away, ask your partner what they observe.
  3. Put the aluminum can on its side on a table. After rubbing the balloon on your hair again, hold the balloon close to the can, then slowly move the balloon away from the can.

Table 1: Visual observations

Step 1
Step 2
Step 3

Experiment B: Conduction

Background information

Electricians take into consideration the materials they are using at all times.

Materials that do not allow a charge to move freely are called insulators. An electrician would use an insulator when he does not want electric charge to travel.

The opposite of insulators are conductors. Conductors are materials that allow charges to move freely. These materials are used in circuitry that allows free-flow of electricity.

Materials that only partially allow electric current to flow are called fair conductors.

Read through the following experimental procedure. Write down a hypothesis of what makes a good conductor and insulator here:

Materials

  • At least four pieces of coated electrical wire (preferably with alligator clips on each end of wires)
  • D battery
  • Small light bulb
  • Testers: paper clip, toothpick, aluminum foil, banana, pop can, copper penny, pencil

Procedure

1.Create a simple closed circuit by connecting two wires to the battery and light bulb. See diagram for example.

2.If not using a bulb holder or battery holder, you can connect the wires by clipping the alligator clip of one wire to the positive post of the battery and the other end to the metal contact (bottom tip) of the bulb. Attach the alligator clip of a second wire to the bottom or negative side of the battery by simply holding the clip in place.(USE CAUTION if holding clip.Heat can be generated.)Attach the other end of the wire to the metal threaded cap of the bulb.If your circuit is correctly closed and a complete path is created, the bulb will light.

3.Next you will test your items to see if they are conductors or insulators.

4.Incorporate one item at a time into your circuit to test if it is a conductor or insulator.Start by disconnecting one alligator clip from the bulb and attaching the clip to the test item.Connect another wire to the test item and then back to the bulb.If the bulb lights, the test item is a conductor.If the bulb does not light, the test item is an insulator. If the bulb is lit poorly, this could be a fair conductor.

5.The following chart is where you will record your observations and data. Simply check off which column correctly describes each item.

Item / Insulator / Fair Conductor / Conductor
Paperclip
Penny
Banana
Pop can
Aluminum foil
Pencil