Pages 78, 78R, and 79 are a simple introduction to electric circuits. Old strings of Xmas tree lights can be cut up; the little bulbs, mounted in sockets with wire leads already attached, are ideal for these experiments. They require 1.5 to 3 Volts, which can be provided with flashlight cells if a DC power supply is not available.

The Chapter 9 Review Sheet should be started now.

On pages 80, 81, and 82 we play with diodes and then figure out how to use an ammeter. It is important for the instructor to check every student's circuit diagram before plugging in anything to avoid burning out ammeters. 82R is an extra help page for those who need it.

On pages 83 and 83R we introduce voltage and voltmeters.

On pages 84, 85, and 86 we introduce electrical resistance.

On pages 87 and 88 we clarify the definition of a “Volt” and then figure out formulas for electrical energy and power. There is a simple electrical heating experiment on 88, which requires a good power supply. 88R and 88RR are extra-help pages.

On pages 89, 89R, and 89b we practice using what we have learned about electrical energy and power.

First March Test with skill sheet and solutions: