Energy and Circuits

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What is energy?

The concept of energy is quite tricky. In Year 8, we teach students that energy is the ability to do work. What is ‘work’ then? In physics, work is defined as the displacement of an object due to the act of a force. Energy is a numerical property that is transferred from object to object and is correlated with movement. For example, the faster particles are moving, the greater the kinetic and heat energy.

There are 2 main forms of energy: potential and kinetic. The Law of Conservation of Energy states that energy can neither be created nor destroyed. Most scientists concede that all energy in the universe was created at the beginning of time itself with the Big Bang. Every object has energy and we can understand this when we look at the atomic structure and the movement of electrons. Energy is released when new chemical bonds are formed and in reverse, energy is used to break chemical bonds.

Of course, we as humans require energy. On the molecular level, we need glucose from carbohydrates and other food groups for cellular respiration. Our body cells takes the energy-rich glucose molecules and combines it with oxygen to make energy in the form of ATP (Adenosine Triphosphate) which is used to power our cells and by extension our bodies!

Glucose + Oxygen → Carbon Dioxide + Water + [ATP (energy)]

World’s Most Asked Question: What is Energy? 

I really enjoyed this SciShow video. What did I learn? Energy is everything.

Energy in circuits

In circuits, there is a transfer of electrons and energy. Today, an English/History teacher said she never really understood how electrons and energy “know” where to go in a circuit. How do they know to evenly distribute themselves in a parallel circuit? The analogy I gave is imagine you have 2 cups sitting next to each other touching and you pour water just over where the two cups touch. How does the water know which cup to go to? Well it doesn’t, it is simply probability. The water has a 0.5 chance of going into the left cup and same with the right cup.

The Galton Board demonstrates this concept beautifully and reveals to us how in a chaotic world, order is created. In the Galton Board, every single time we rotate it we see the same pattern: a normal distribution. The question we ask ourselves is, “How does the bead know where to go?”. Of course, it doesn’t know. Each bead has an equal probability of going left or right as it bounces on each peg. By pure probability, the beads rearrange themselves in an aesthetic bell-shaped curve.

Galton Board

Find out more: The Galton Board

Role Play: Minties 

In teaching the movement of energy in a circuit, I used a role play activity using Minties. Minties are an Australian mint-flavoured lolly. Of course, other lollies or equipment can be used as a substitute. 🙂

A single lolly represented a Joule of energy. A giant series circuit diagram was drawn on the quad at school using tape. This represented the lead or conductive wire. A few students were selected to represent various components of the circuit: battery, ammeter and light bulb(s). Other students stood on the lead/wire and they walked around the circuit to represent electrons. The battery provided students with 2 Minties each. The students had to carry their Minties around the circuit and give their Minties to the light bulb, which would then glow (The light bulb student might wave their arms or say “Ding!”). Variations used in this role play included adding a light bulb in series where students had to give 1 Mintie to each light bulb, and creating parallel circuits where students would have a 50/50 choice of where to go.

This was a fun activity where students were able to visualise energy transfer and even energy transformation (where the light bulb glowed). A trickier concept was the idea that given two light bulbs, light bulbs in series would shine less brightly (as energy was shared between the light bulbs) than if the light bulbs were in parallel (each light bulb was given 2 Minties each).

A colleague showed me a wrapper game that kids can play after they ate their Minties. Taking the wrapper, rip the wrapper around the perimeter and try to obtain the longest piece of wrapper. This could be used as a lesson finisher!

Creating a Torch

Students l o v e d making their own torches. This was where students really demonstrated their understanding of how a circuit worked as well as energy transformation. Students exercised great team work and communication skills. Students were given 2 pins, a AA battery, leads, a piece of cardboard, alligator clips and a paper clip. Hints were given along the way to guide them on the project. Students lit up (ha!) when they figured it out and began to experiment with multiple batteries and light globes to see the effect of adding more components into the circuit.

DIY Simple Torch

Let me know if you have other ideas about teaching the concept of energy and energy transfer!

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