Year 9 are designing an LED desk light and need to understand why every LED needs a current-limiting resistor. Through the teacher-managed Tinkercad class, each student wires a 9 V battery, a resistor and a red LED with a multimeter in series, then runs the simulation with five resistor values from 100 ohms to 10 kilohms. They record the current and how bright the LED looks in a table in their books, and notice from the meter that at 100 ohms the current is far above the 20 milliamp maximum for a typical red LED. Students then use Ohm's law to calculate the value they would choose, (9 V - 2 V) / 0.02 A = 350 ohms, and check in the simulation that the next standard value up, 390 ohms, keeps the current under 20 milliamps, where rounding down to 330 ohms would not. The teacher goes over the calculation at the end and marks the tables after the lesson.
Tools: Tinkercad Nine ideas for your own version in Generate
This page is one of a growing set of PICRAT examples by cell, subject and grade. Page maintained by Andy Perryer.