Lesson Plan

• Describe the concept of charge quantisation and the elementary charge e.
• Identify common charge carriers and state their integer charge values.
• Explain experimental evidence for charge quantisation (Millikan oil‑drop, photoelectric effect).
• Calculate the number of charge carriers associated with a given current using I/e.
• Apply charge‑quantisation ideas to solve basic current‑carrier problems.

• Projector or interactive whiteboard
• Slide deck with diagrams of charge carriers and the Millikan experiment
• Printed worksheet with practice calculations
• Colored tokens or cards representing different charge carriers
• Scientific calculators (one per student)
• Exit‑ticket cards

Begin with a quick question: “If you could split an electron, what would you get?” This hooks curiosity about charge limits. Review the definition of electric current and the units ampere and coulomb. State that today’s success criteria are to explain why charge comes in whole multiples of e and to use that idea in calculations.

1. Do‑now (5 min): short quiz on current, charge, and units.
2. Mini‑lecture (10 min): introduce charge carriers, elementary charge e, and the quantisation formula q = n e.
3. Demonstration (8 min): video/animation of the Millikan oil‑drop experiment; discuss how integer multiples of e were observed.
4. Guided practice (12 min): pairs calculate the number of carriers for given currents using N = I/e; teacher provides feedback.
5. Concept check (5 min): think‑pair‑share on why fractional charge is not observed in macroscopic matter.
6. Application activity (10 min): use tokens to model charge flow and relate token count to macroscopic current.
7. Summary & exit ticket (5 min): students write one key takeaway and answer a brief question on charge quantisation.

Recap that all observable charge is an integer multiple of the elementary charge and that this principle links microscopic carriers to the macroscopic current we measure. Collect exit tickets to gauge understanding, and assign a homework task to solve three current‑carrier conversion problems.