Unit D: Electrical Principles and Technologies

 Learning Targets

Pre-assessment: What do you know?



Figure D.P.1 – Electrical devices change electrical energy into different forms of energy.

Figure D.P.2 – Circuits control the flow of electric current.

Electrical technologies have greatly changed the lives of humans. Electrical energy is so useful because it can be changed into other forms of energy, to do useful work. The ability to control electricity in circuits allows people to do less physical work, to travel farther, and to communicate faster. Daily human life is much easier with electricity.


Figure D.P.3 – Electrical devices can be dangerous if they are not used safely.
However, there are some drawbacks to modern electrical use. Electrical devices can harm people if they are not used safely. Some methods of generating electricity can have negative effects on the environment.

All devices waste electrical energy, some more than others. Scientists and engineers are developing new methods to generate electricity with a lower impact on the environment.

  • How do different types of circuits control electrical energy?
  • How do power companies calculate the amount of electrical energy a household uses?
  • How do we use electricity safely?

To learn more about how we can generate and use electricity while reducing our impact on the environment, we must understand how electrical principles and technologies work.


Figure D.P.4 – Hydroelectric dams generate electricity.

Figure D.P.5 – Wind turbines generate electricity.

Pre-assessment Questions & Hints

Step 1: The Questions


This short pre-assessment is to find out what you might already know about the topic of . Below are four questions. Think about them! If you need a hint, click on the question.

Optional: If you would like a place to write your answers, download this document. If you prefer to use a Google Drive or PDF version of this pre-assessment, click here.

Step 2: The Answers

 Click each of the suggested answers below – how do they compare to your thoughts and answers?
Voltage describes the energy per unit charge in a circuit. Current is the amount of charge per second that runs through a circuit. Resistance describes how easily a material lets electrons flow through it. In a circuit, the voltage is equal to current multiplied by resistance, or V = IR.
Electrical energy can be changed into many different types of energy. For example:
  • Light bulbs change electrical energy in light.
  • Speakers change electrical energy into sound.
  • Motors in appliances like blenders and fans change electrical energy into movement.
  • Ovens and toasters change electrical energy into heat.
All electrical devices produce some wasted energy as heat. Electrical devices that produce a lot of heat waste a lot of electrical energy.
Humans use several ways to generate electricity, including:
  • Hydroelectric dams
  • Coal-fired power plants
  • Wind turbines
  • Nuclear power plants
  • Solar panels

Some of these electrical generation methods have negative impacts on the environment, including:
  • Coal-fired power plants release carbon dioxide into the atmosphere, which contributes to climate change
  • Building hydroelectric dams floods land and destroys ecosystems.

Step 3: Check In With Your Teacher

The start of a new unit is a great time to touch base with your teacher! Here are just a few reasons to consider contacting your teacher:

  1. Perhaps you found this pre-assessment quiz very easy because you have studied this material before, such as at another school. If so, it's important to tell your teacher.

  2. It's very good for your teacher to know you are starting a new unit; it will give them a good idea of your progress. It doesn't have to be a long message, just a "I'm starting Unit A; just thought you might want to know!"

  3. Your teacher may have special tips and suggestions for the unit you are starting.

  4. Just to say hi – your teacher always enjoys hearing from you!

To contact your teacher, post in the Course Questions Forum, send your teacher an email, or call on the phone if you like. Whatever way you choose, it's always a good idea to get in touch with your teacher – make sure you do it frequently.