Performance-Based Assessments for Basic Electricity Competencies

Use a variable-voltage, regulated power supply to supply a suitable DC voltage for the incandescent lamp.

Use a variable-voltage, regulated power supply to supply any amount of DC voltage below 30 volts. Specify a standard resistor value, somewhere between 1 kΩ and 100 kΩ (1k5, 2k2, 2k7, 3k3, 4k7, 5k1, 6k8, 10k, 22k, 33k, 39k 47k, 68k, etc.).

If using this question as a lab exercise rather than an assessment, I recommend specifying a voltage that is standard for batteries, so students don’t necessarily have to have an adjustable power supply available to do this lab.

For example, specify V_supply as 6 volts and R₁ as 33 kΩ. The resulting current is sufficient to provide a nice, strong needle deflection on most cheap analog ammeters, too!

The purpose of this exercise is to make absolutely sure students can accurately measure resistance with a multimeter, and also that they can interpret resistor color codes. Select resistors that span a wide range, from less than 10 ohms to millions of ohms.

I recommend the following resistor color codes for students to try (all 5% tolerance):

• Blk, Brn, Grn, Gld

• Brn, Red, Brn, Gld

• Blu, Gry, Blk, Gld

• Red, Red, Org, Gld

• Brn, Grn, Yel, Gld

• Org, Org, Red, Gld

A good extension of this assessment is to have students demonstrate competency using both digital and analog multimeters!