Ohm's law resistor calculation with the BBC micro:bit
Developing a prototype for an LED based automatic home lighting system
In this activity students will learn about importance of and use Ohm’s law to calculate the value of a protective resistor for an LED. Using a BBC micro:bit, they will develop a prototype for an LED based automatic home lighting system, designed to save energy.
This prototype aims to promote energy efficiency, a concern that resonates with our daily life as it's estimated that the average UK homeowner could save up to £240 a year alone on the cost of lighting their home.
This is one of a set of resources developed to aid the teaching of the secondary national curriculum, particularly KS3. This is part of our series of resources designed to support the use of the BBC micro:bit in secondary school design & technology (DT), computing and engineering lessons. It can also be used to support physics sciences lessons.
Activity: Developing a prototype for an LED based automatic home lighting system
In this sustainable lighting activity, students will be tasked with creating a smart lighting system that adjusts based on environmental conditions.
This involves programming a BBC micro:bit microcontroller to control the lighting system and using various sensors to detect changes in the environment. For instance, they might use a light sensor to detect when it's getting dark outside and automatically turn on the lights. In addition, they could use a motion sensor to detect when someone is in the room and turn the lights off when no one is there to conserve energy.
A crucial part of this task will be applying Ohm's law, which states that the current through a conductor between two points is directly proportional to the voltage across the two points. Students will calculate the appropriate resistance needed for their circuit to ensure the LEDs function correctly without overheating or burning out. This will involve determining the correct resistor values and understanding how they affect the overall performance of their lighting system.
The engineering context
Engineers are often required to program devices to perform specific tasks, optimise system performance, or even create entirely new technologies. This involves understanding how to embed intelligence into products, which can range from simple household items like automatic lighting systems to more complex systems like autonomous vehicles or smart city infrastructure.
By learning programming skills and understanding how to integrate them into engineering projects, students will gain an insight into how different components can work together in a system.
Furthermore, resistors are essential components in electronic circuits, controlling the flow of electricity and protecting components from damage by limiting the current. Understanding Ohm's law and resistor calculation will lay the groundwork for many aspects of electronics and electrical engineering.
Suggested learning outcomes
By the end of this activity, students should be able to understand and apply Ohm’s Law, particularly in calculating the value of a protective resistor for an LED. The skills they acquire will extend beyond the classroom, equipping them with practical knowledge that can be applied in real-world situations. This activity will also set a solid foundation for more complex electronic theory lessons or when delving deeper into the relationship between voltage, current, and resistance.
Download our activity sheet and other teaching resources
The activity sheet includes teachers’ notes, useful web links, and links (where appropriate) to the national curriculum in each of the four devolved nations; England, Northern Ireland, Scotland and Wales.
All activity sheets and supporting resources are free to download, and all the documents are fully editable, so you can tailor them to your students’ and your schools’ needs.
Download our classroom lesson plan and PowerPoint presentation below.
Please do share your highlights with us @IETeducation.
