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