Req 2 — Forms & Conversions

This requirement has two parts that belong together. First, you explain how real devices change energy from one form to another. Then you build a simple system that does at least two conversions so you can see the idea happen in front of you.

• Requirement 2a is about reading devices like energy maps.
• Requirement 2b is about making a conversion chain yourself.

Requirement 2a: Explain three devices and their conversions

The easiest way to explain a device is to track three things: the input energy, the useful output, and the losses. If you can name those clearly, you usually understand the conversion.

Here are a few examples from the list:

• Toaster: electrical energy becomes thermal energy in the heating elements. The useful output is heat that browns bread. Some energy is also lost by warming the surrounding air.
• Lightbulb: electrical energy becomes radiant energy and thermal energy. In older incandescent bulbs, a lot of the energy becomes unwanted heat.
• Bow drill: chemical energy in your body becomes mechanical energy in your arms, then thermal energy from friction, which heats tinder until it can catch.
• Cell phone: chemical energy stored in the battery becomes electrical energy, then turns into light, sound, radio signals, and heat.
• Electric vehicle: chemical energy in the battery becomes electrical energy, then mechanical energy in the motor and wheels. Some energy is lost as heat in the battery, wiring, and tires.

A greenhouse is especially interesting because it reminds you that not every system uses electricity or fuel directly. Sunlight enters as radiant energy, warms surfaces and air inside, and helps keep the greenhouse warmer than the outside environment.

What makes a strong answer?

A strong answer sounds like an explanation, not a label. Do not stop at “A toaster uses electricity.” Go one step farther: “A toaster uses electrical energy in resistive heating wires. Those wires get hot and transfer thermal energy to the bread. Some energy also warms the surrounding air, which is a loss.”

Requirement 2b: Build a system with at least two conversions

You do not need a huge engineering project to complete this part. You need a safe, clear system that lets you point to the conversions. The more visible the conversions are, the easier your explanation will be.

Good project ideas include:

• a rubber-band car: chemical energy in your body winds the band, elastic potential energy is stored, then becomes motion and heat from friction
• a solar toy or solar fan: radiant energy from sunlight becomes electrical energy, then motion
• a battery-LED buzzer system: chemical energy in the battery becomes electrical energy, then light and sound
• a small water wheel model: gravitational potential energy of water becomes motion, then maybe electricity if attached to a generator kit

How to present your build

When you show your system, tell the story in order:

1. Where does the energy start?
2. What stores or carries it?
3. What conversions happen next?
4. What useful result do you get?
5. Where is energy lost along the way?

You can now describe what energy does inside a device. Next, you will zoom out and look at a whole system to see where energy helps, where it is useful, and where it leaks away.