PC Hardware

Lesson Summary: The Basics of Electrical Energy

The following point summarizes the main elements of this lesson:

  • Electrical safety is your responsibility. Be sure to follow all safety guidelines listed for the devices you work with, and do not work inside of products such as monitors or power supplies without special training.

Tutorial Summary

The following points summarize the key concepts in this tutorial:


  • Ohm's Law states that the current flowing through a conductor, or resistance, is linearly proportional to the applied potential difference (volts).

  • Electricity is delivered to our homes and businesses as AC (alternating current). Computers use DC (direct current).

  • Electricity always seeks the path of least resistance to ground. An electrical outlet or an extension cord without a ground wire is unacceptable for use with a computer.

  • A multimeter is an instrument used to measure electrical voltage, current, resistance, and continuity.

Electrostatic Discharge (ESD)

  • Electrostatic discharge (ESD) depends on the types of materials and the amount of friction involved, the humidity, and how quickly the energy is released. ESD can cause damage to computer parts. Always take preventive measures when working around a computer.

Safety and Electrical Power

  • It is vital to follow basic electrical-safety guidelines when working around electrical and electronic devices. Remember-electrical safety is your responsibility.


  1. What is Ohm's Law?

  2. What is the formula for Ohm's Law?

  3. What is the difference between AC and DC?

  4. What instrument is used to measure the various components of electricity?

  5. How do you test for continuity?

  6. What is "AC Ripple?" How do you test for it?

  7. Describe ESD and how to prevent it.

  8. What is a latent failure? What makes it especially troublesome?

  9. What is a catastrophic failure?

  10. When working with a computer, when is it acceptable to use an AC power supply that is not grounded?