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Electronics lab: sensors, transistors and logic gates

Street lights that switch on at night and phones full of tiny switches: build simple electronic circuits and the logic behind them.

▶ Start the lab🧠 Questions📄 My report
💡V = V₀ R₂ ÷ (R₁ + R₂)sensors, transistors, logic gates
LevelS3 to S6 (and IGCSE, A Level)
TimeAbout 35 min
You usePotential divider, truth tables
PriceFree: no account

🎯 Aim

To investigate a light-sensing potential divider with a transistor switch and the truth tables of logic gates.

You will learn to

  • Calculate voltages in a potential divider.
  • Explain how an LDR and a transistor make an automatic switch.
  • Use diodes and choose an LED resistor.
  • Complete truth tables for logic gates.

🧭 What to do

  1. Lower the Light level until the lamp comes on.
  2. Change the fixed resistor R₁: when does it switch now?
  3. Choose a Gate and change Input A and Input B.
  4. Read the truth table of each gate.
  5. Answer the questions with the class data.
  6. Write your conclusion and download your lab report.

🔬 Lab bench

📋 The data

Components of an automatic street light.

🧠 Investigate: answer from the data

Type your answer and tap Check. Use 💡 Hint first; open the method only when you are stuck.

📄 My lab report

Your report collects the aim, your data table, the graphs, your answers and your conclusion. It is made on your phone or computer: nothing is sent to anyone.

Check your conclusion

In the dark the LDR’s resistance rises, so it takes a bigger share of the 6 V; above about 0.7 V the transistor switches on and the lamp lights. A diode lets current pass one way. Logic gates combine 0s and 1s: AND needs both inputs, OR needs either, NOT inverts, and every gate can be built from NAND gates.

➕ Get more from this experiment

📝 Free

Print the worksheet (button above), download the data, and save your report. Teachers can project this page in class.

📦 Premium Lab Pack

1 000 RWF

  • Practical worksheet: an LDR night light with a breadboard
  • Electronics and logic problems
  • Teacher guide and answer key
  • Exam-style questions with marking scheme
See the pack

👩‍🏫 For teachers

Use it as a practical when apparatus is missing, as homework, or as a project. Free lesson plans help you plan, teach and assess.

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