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Year 8 · Design and technology · CAD and electronics · Lesson 4

Sensors and designing an electronic product

Sensors (LDR, thermistor, switches), transistors and microcontrollers, and designing an automatic night-light from specification to testing and evaluation.

Whiteboard video lesson: Sensors and designing an electronic product

17-minute video lesson

Teaching, worked examples and 20 practice questions solved step by step.

Watch free for a month

What your child will learn

  • Explain how LDRs and thermistors work
  • Compare transistors and microcontrollers
  • Plan a product with a systems diagram
  • Write a specification and evaluate against it

The method

  1. Need + user.
  2. Specification.
  3. Plan.
  4. Make, test, evaluate.

Key words: sensor, LDR, thermistor, transistor, microcontroller, specification, night-light.

Worked examples

The first three practice questions from the lesson, with every step.

Question 1

What does LDR stand for?

  1. Step 1: Light...

Answer: Light-Dependent Resistor

Question 2

What happens to an LDR's resistance in the dark?

  1. Step 1: Up or down?

Answer: it increases (goes high)

Question 3

What does a thermistor sense?

  1. Step 1: Hot or cold

Answer: temperature