• First Steps in Ham Radio - a series of articles intended to help you get started.
• ARRL Technical Information Service - numerous links and articles on a variety of technical topics
• The ARRL Handbook - the oldest and best radio handbook around
• Understanding Basic Electronics - introduction to the electronics of radio

• A Helpful Discussion about Power and Decibels
• A Helpful Discussion About Converting Units
• Tutorial on Scientific Notation
• The Metric System
• Tutorials on Math for ARRL On-Line Courses and License Exams

Here are some alternative tutorials on voltage and current:

• Sparkfun - Voltage, Current, Resistance, and Ohm's Law
• Study.com - Relationship between Voltage, Current, and Resistance

This Ohm’s Law tutorial explains where Ohm’s Law comes from and shows how to use the Ohm’s Law circle for problem solving.  The Wikipedia entries on electrical power and the Watt explains how power is calculated and the difference between power and energy.

The worked-out solutions to each of the Technician exam problems involving Ohm’s Law and power are at the bottom of this web page .  This online calculator is also handy for solving Ohm’s Law and power problems.

Power line frequency in North and South America is generally 60 Hz while other areas of the world use 50 Hz.

The different types of resistors are illustrated on Wikipedia and theseYouTube videos explains what resistors are and the resistor value color code.  Potentiometers (variable resistors) or “pots” are explained in this tutorial. This article from the ARRL’s “Lab Notes” series discusses capacitors. Here’s an article on the color codes that designate the value of electronic components by their colored markings.

This “How Stuff Works” page explains the basics of semiconductor components like diodes and transistors without going into unnecessary detail.

More "How Stuff Works" pages explain the basics of fuses, circuit breakers and surge protection.  Ground Fault Circuit Interrupter (GFCI) circuit breakers are discussed separately. The ARRL Handbook also covers these components in the Electrical Fundamentals chapter and the Safety chapter.  Grounding and the difference between Earth and chassis grounding are explained here.

The ARRL’s Technical Information Service includes the articles How to Read Circuit Diagrams, Part I  and How to Read Circuit Diagrams, Part II.  The articles may be old, but they are accurate!

The Wikipedia entry on “superhet” receivers covers how they work and a bit of the history of how they came to be.

Technician Exam Power and Ohm's Law Problems - a downloadable PDF showing how to work the problems