Physical Science                                         Circuit Lab

Before you start to build circuits, let's take a look at a circuit diagram (that's just a diagram used to illustrate how you connect the components). To help you record the circuits you create, each component in a circuit diagram is represented by a symbol. Using the symbol makes it easier to “draw” what you have created or express what you intend to create. The diagram to the right shows the components and the symbols used to represent them.

 

MATERIALS

Popsicle stick, string, paperclip, staple, pencil eraser, D-cell battery, light bulb, insulated wire, and several other items to test for conductivity (various items typically found in a student book bag)

 

PROCEDURE

Part I. Conductors and Insulators

  1. Using the materials listed above, construct a circuit, which could be represented by the following drawing.

Switches are simply breaks in a circuit. When a circuit is broken, the circuit is said to be open. In an open circuit, electrons cannot flow and return to the positive pole of the battery.

 

  1. Answer this question: How do you think you might be able to create a closed circuit using the diagram from above?

__________________________________________________________________

  1. Between points A and B on the diagram there exists a switch. Using the materials listed above close the circuit. Test the various materials to see whether they are conductors or insulators. Record your data in the following table.

Materials

DOES THE BULB LIGHT UP?

Popsicle Stick

 

String

 

Paper Clip

 

Staple

 

Pencil Eraser

 
  1. Try other materials and complete the chart on the following page. If you require more space to record your results, create another table on a separate piece of paper.

Materials

DOES THE BULB LIGHT UP?

 

 

 

 

 

 

 

 

 

 

 

 
  1. After you have tested all your list, classify the materials into the two following categories:

CONDUCTIVE MATERIALS

(conductors)

Bulb lights!

NON-CONDUCTIVE MATERIALS

(insulators)

Bulb does not light!

 

 

 

 

 

 

 

 

 

 

 

 
  1. Answer the question: Why do you think the connecting wires are made of copper, yet they are covered with a piece of flexible plastic?

 

 

Part II. Switches in Circuits

  1. How do you think a switch works?

 

 

  1. Construct a switch using a paperclip and two wires. (see diagram)

  1. Build the following circuits: List what you observe happening to the brightness of the light during each in the following data table.

Circuit

Observations

 

 

 

 

Part III. Series and Parallel

  1. Hook the lights up to one battery in series then in parallel. Describe the difference.
  2. Hook two batteries together in series and parallel to one light. You might need to team with another group to share batteries. Describe the difference you observed from just hooking up one battery to the light bulb.

 

SERIES

PARALLEL

1 battery and 1 light bulb

 

 

Used for control purposes.

1 battery and 2 light bulbs

 

 

2 batteries and 1 light bulb

 

 

 

 

Part IV. Creating your own Circuit Board

  1. Obtain from your teacher the following items:

two pieces of cardboard, two strips of aluminum foil backed with tape, some brass fasteners, four lights and a battery (students may share a battery).
*Other materials not provided must be brought from home.

  1. Construct a series circuit board with two lights and a switch. On your board, leave a place for the battery to connect to the circuit. You may want to have leads, connectors to hold the battery or just a spot to hook up the wire; the choice is yours as the circuit designer.  You may use other materials not provided by the teacher.
  2. Using the other piece of cardboard you must now design a circuit with two lights that will be a parallel circuit board. You must include some type of switch. Complete this one as you did with the previous board.
  3. Diagram each of your circuits below:

Series Circuit

Parallel Circuit

 

 

 

  1. What happens to the lights if you put two batteries together in series when you hook them up to the bulbs?

__________________________________________________________________

  1. What happens to the lights when you hook up the two batteries up in parallel?

__________________________________________________________________

 

ANALYSIS/CONCLUSION QUESTIONS

Directions: Write your answers on a separate sheet of paper and attach if necessary.

  1. What types of materials make good conductors?
  2. If a material were not a good conductor of electricity would it automatically be a good insulator for heat? Explain your answer.
  3. How many different kinds of electrical switches can you find in the classroom? In the school? At home? Make a list and briefly describe the difference.
  4. Take a look at flashlights. Can you find the switch in a flashlight? Are all flashlight switches the same?
  5. What is the purpose of switches in most circuits?
  6. List at least two other simple circuits (not including a flashlight).
  7. What would be the advantage of hooking up two batteries together in series over hooking up only one to the circuit? What would happen if one went dead?
  8. If you hooked up two 1.5 V batteries together end to end (in series) in a circuit, what would be the potential difference in the circuit?