Electrical energy
Electrical energy also has many forms. For example, lightning, is a form of static electricity. You witness static electricity also when you rub a balloon against your hair. One of the most useful forms of electrical energy for humans is when it is generated from a current, which occurs when electrons flow through a circuit. It is the form that we use to power all our devices such as computers, TVs, phones, smoke alarms and electric vehicles. In whatever form electrical energy takes, it involves the movement of electrons in one direction. Learn more about electricity and how it is generated in our unit on conductors, insulators and electricity.
Electrical energy is a form of potential and kinetic energy. A charged particle such as an electron has potential energy when it is stationary within its atom. (Note: an electron is never really stationary. They always jiggle a bit, even when cooled to near absolute zero (Absolute zero = -273˚ Celcius.) If we apply a force, such as the chemical energy from a battery that is connected to a conducting material that is part of a closed circuit, the electrons move in one direction through that conducting material and generate a current. The electrons now have kinetic energy. We measure electrical current in amperes (amps), which is the rate that electrons move through a circuit.
The higher the rate of electrons passing through a circuit, the higher the amps and the higher the amount of electrical energy is generated. One ampere of current flowing through a circuit for a second with one volt applied is equivalent to one joule. However, while the moving electrons have kinetic energy, it is not the energy that is powering your electronic devices. The flow of electrons (charged particles) is just what enables the electric energy to flow, which is generated from the electric fields generated by the battery and the surface charges on the circuit once the circuit is closed. What is happening here is quite complex and nuanced as evident in a debate that arose from a thought experiment created by Derek Muller from Veritasium, which sparked a series of follow up videos, many refuting Derek’s conclusions. This led to this follow up video from Derek, which explains what is happening in a circuit quite well.*
*The Science Asylum (below) also has a good explanation of where energy comes from in a circuit. *Note these two videos are pitched at approximately year 10 and higher.
Earth, we have a problem
We use electrical energy to power all our electrical equipment that the world now relies on. A lot of that electrical energy is consumed by digital technologies – or computing. That is, anything with a computer chip in it, which today includes cars (about 100 in a modern car), doorbells, cameras, fridges, toasters, coffee makers, watches, phones, oh and computers…..so many things.
The proportion of global energy consumed by digital technologies is continuing to increase rapidly each year and is predicted to soon become unsustainable. That is, the world won’t be able to generate enough energy to meet the energy demand from digital devices. This is the motivation for FLEET’s research. FLEET is developing novel materials at the atomic scale that will conduct a current without energy loss. Remember the heat you feel from your laptop or mobile when you use it? That is lost or wasted energy. What would the implications be, if we could conduct electricity without resistance (energy lost as heat)? Essentially, you would require less voltage or initial energy to do the work required. For example, if your device requires X Joules to do the necessary computation, then you need to generate the equivalent of X+1 Joules because the +1 will get lost as heat in the circuits. Or instead of using a 9 volt battery, you only need a 1.5 volt and the battery might last longer before needing to be replaced.
These novel materials will be used to replace silicon in transistors (the brains in your computer chip), circuits and memory storage devices. See more on FLEET’s research to tackle this problem here.
To get students to consider how we use energy and what are acceptable means to achieve sustainable energy use, they can do the critical thinking exercises in Activity 9.
Energy and Power
Students will likely associate the concept of energy with power. Power and energy are different concepts. As noted, energy is the ability to do work or cause change. For example, lifting a weight in the gym requires a certain amount of energy to be available; a battery, or an item of food we could eat will hold a certain amount of energy.
Power, on the other hand, is the rate that the energy is used or transformed from one form to another. For example, to lift a weight your body will burn a certain number of calories (energy) per minute or hour (time). A light bulb will use a certain amount of electrical energy per unit of time to provide the necessary light. The heavier the weight or more intense your workout, the more energy per unit of time you will use. The more powerful the light bulb, the more energy (watts) it will consume per unit of time. The power is the amount of energy used per unit of time. Or, it is the rate at which work is done.
While this resource will not cover in any detail the difference in power and energy, it is an important distinction for students to understand.
Ok, now it is time to examine energy from the quantum perspective because it is what underpins so many of the technologies that we interact with on a daily basis – from solar panels to your smart phone.
Next up: Quantum energy
Head to Quantum energy. Or back to FLEET Schools Forces and energy; FLEET Schools