Product: Inquiry Lab Template

A series of 3 labs (based significantly on the CASTLE curriculum) that help teach the basics of circuits. These labs assume the students already have experience with conductors and insulators.

Grade Level/Subject / Physics (all levels)
Unit / Circuits
Enduring Understanding / Charge exists everywhere in a circuit. A power supply gives these charges energy, which may then be converted to other forms of energy.
SOL Objectives / PH.11 The student will investigate and understand how to diagram, construct, and analyze basic electrical circuits and explain the
function of various circuit components. Key concepts include
a) Ohm’s law;
b) series, parallel, and combined circuits;
c) electrical power; and
alternating and direct currents
Title / Intro Circuits
Lesson Objective / Learn the basics of circuits (charge travels one way, charge is conserved, battery is a source of energy, charge is already present in circuit)
Inquiry Level / 2
Materials Required /
  1. Basic material from CASTLE program (sold by PASCO) including light bulbs and sockets
  2. Wires
  3. power supply
  4. compass
  5. genecon

Circuit Basics Lab 1

PART A:

  1. Build the following circuit:
  1. “Break” the loop by disconnecting a wire from one end of the power supply; then reconnect the loop.

a)Do you see both bulbs light at exactly the same time?

b)Do you believe that both bulbs actually light at the same time?

c)Do both bulbs appear to go out at exactly the same time?

  1. Reconnect the wire to the power supply, and then disconnect a different wire somewhere else in the loop. Try doing this in several places. Be sure that you have only one break in the loop at a time.

a)Is there any place where you can break the loop and one or both of the bulbs will still stay lit?

  1. Unhook any wire and then bring it back as close as you can to where it was connected —without actually making contact. Do this slowly and carefully, watching the space between the wire and the contact point.

a)Do the bulbs light?

b)Do you think actual contact is needed for the bulbs to light continuously?

PART B:

  1. Build the following circuits and note whether the light bulbs turn on or not.

Circuit A:


Circuit B:


Circuit C:


2. Based on the experiments so far, what factors must be met in order for the light bulb to light?

PART C:


Study a light bulb and determine how many distinct sections or parts exist on the external frame of the light bulb. Label each part (with a good, descriptive name) on the diagram below.

PART D:

Using your test circuit above, determine if each part you labeled allows electricity to flow.

Part of Bulb / Lights?

Circuit basics lab #2

Inside the wires:

This lab uses a magnetic compass to detect electrical activity inside the wires. Read and follow the directions carefully when you set up this part, or it simply won’t work.

1)Place the compass on the table top, as far away as possible from any metal parts. Tape the compass to the table — masking tape works best. (Place a rolled piece of masking tape below the compass.) Note that the compass is not connected to any wire. It is a detector for what is happening in the wires. Note the direction that the compass needle is pointing.

2)Connect your power supply, two light bulbs, and wires to make a single loop, as before. Keep it turned off for now.

3)Rearrange your loop over top of the compass so that one segment of wire is laying over the compass, exactly PARALLEL to the direction that the compass needle is pointing, as shown. Keep the power supply as far away from the compass as reasonably possible (use long wires).

4)Turn on the power supply and note the behavior of the compass. Turn it off and on several times and observe. Explain what is happening.

5)Record the direction (clockwise or counter-clockwise) and amount (angle) of deflection of the compass.

6)Is there any evidence that something is happening in the wire over the compass during the time the loop is broken? What is the evidence, for or against?

7)For the next section, do NOT move the compass that is taped to the table. Instead, with the power off, rotate the entire wire loop so that the middle wire is now over top of the compass, and parallel to the needle.

8)BEFORE you connect the circuit, make a prediction about which way the compass needle will rotate when you turn the system on.

Prediction: ClockwiseCounter-clockwise
Actual (direction and magnitude):

9)Rotate the entire loop again, so that the third wire is over the compass (Figure 1.2c). Predict what you will observe when you connect and disconnect the loop again, and observe the compass. Then try it.
Prediction: ClockwiseCounter-clockwise
Actual (direction and magnitude):

10)Looking at your results from all three wire segments, what similarities and patterns do you see?

11)Do you think the same thing is happening in the wires all the way around the loop? Why?

12)Next, reverse the orientation of the power supply — by disconnecting the wires from the supply and then reconnecting them at opposite terminals. Before doing so, predict what you will observe.

Prediction: ClockwiseCounter-clockwise
Actual (direction and magnitude):

13)How does this compare with the compass deflection when the power supply was connected the opposite direction?

14)Examine the compass deflections in the other two wires now that the battery has been reversed. What do you observe?

15)What do you think might be happening in the wires to make the compass deflection change direction when the battery orientation is reversed? Explain your reasoning.

16)Some people suggest that there is something moving in the wires. Is there any direct evidence of this? Explain.

17)If something is moving in the wires, does the direction of movement and the amount of movement appear to be the same in every wire of the circuit at one time? What is the evidence?

18)What do you think the battery does in this circuit? What is the evidence?

19)Some people mistakenly think that charges get “used up” as they go through a circuit. Explain how the results of this investigation will refute this common misconception.

Circuit Basics Lab 3

  1. Build the following circuit. Notice that there is NOT a battery in this circuit; instead there is a Genecon.
  1. Turn the crank on the Genecon at a steady rate of one or two revolutions each second, and feel the effort needed for lighting the bulbs.
  1. Unscrew one of the bulbs enough to break the circuit then turn the crank on the Genecon for about ten seconds. Is it easy or difficult to turn the crank when the circuit is broken?
  1. Turn the bulb back in to complete the circuit, and turn the crank at about the same speed as before.
  1. Is there any difference in the “effort” required to keep the Genecon turning at the same speed?
  1. Since the bulbs light, what can you conclude about what a Genecon does?
  1. Now build the circuit shown to the right, set the power supply to 2 V and observe the brightness of the light bulbs.
  1. Replace the power supply with the Genecon and crank the Genecon until the bulbs have the same brightness as they did in step 7. During ten seconds, approximately how many turns of the crank do you have to make in order to maintain this brightness?
  1. Repeat step 7 with the power supply set to 4 V. Predict how many cranks of the Genecon it will take during a 10 second period to produce this same brightness. Then test your prediction.

Prediction:

Actual:

  1. Repeat again this time with the power supply set at 6 V. Predict how many cranks of the Genecon it will take during a 10 second period to produce this same brightness. Then test your prediction.

Prediction:

Actual:

  1. When using a Genecon, where does the charge originate that moves through the bulbs?
  1. A hair dryer is a pump for air. A vacuum cleaner is also an air pump. Do a battery and a Genecon act like a pump for charge? Explain.
  1. How is increasing the “size” of the power supply similar to cranking a Genecon faster?