## Interactive Circuits Lab

Today in PAE, we did an interactive circuits lab. I assigned the students to create 3 different circuits from the PHET Interactive Circuit Construction Kit: DC – Virtual Lab hosted by University of Colorado – Boulder.

Circuit 1 was a simple series circuit consisting of two lights, two batteries, and a switch:

Circuit 2 was a somewhat easy series circuit consisting of one light, three batteries, a switch, and a 120 Ohm resistor:

Circuit 3 was a parallel circuit consisting of three lights, each controlled independently with a switch:

Circuit 4 was a parallel circuit identical to circuit 3, but had a series “master switch” in it:

Circuit 5 was a short circuit with an over-heated power supply:

The students appeared to have fun with the lab and were engaged the entire class time. Thank you UC-Boulder for this nice interactive tool!

## Working with Resistor Color Bands

Today, in PAE, we did a lab where we were looking at resistor color bands.

With this particular resistor, we have color band 1 is green, color band 2 is violet, color band 3 is red, and color band 4 if silver.

On bands 1 and 2, the colors represent the following:

 Color Value Black 0 Brown 1 Red 2 Orange 3 Yellow 4 Green 5 Blue 6 Violet 7 Gray 8 White 9

The 3rd band represents the multiplier.

 Color Value Black 1 Brown 1 x 101 Red 1 x 102 Orange 1 x 103 Yellow 1 x 104 Green 1 x 105 Blue 1 x 106 Violet 1 x 107 Gold 1 x 10-1 Silver 1 x 10-2

The final band relates to the tolerance.

 Color Value Blank +/- 20% Silver +/- 10% Gold +/- 5%

So, the example above would be the following values:

5 , 7 , 1 x 102 , +-/10%

That would be 57 x 1010Ω with a tolerable variance of +/- 10%.

10% of 57 x 1010Ω is 57Ω. So to calculate the total range, we would do the following:

57 x 1010Ω + 57Ω = Upper Range

57 x 1010Ω – 57Ω = Lower Range

So, the resistor in the example would have a total operating range of:

627Ω to 513Ω