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What do the common electronic components do, and how are they used in a circuit?

Electronic components: resistors, capacitors, diodes and LEDs, transistors and integrated circuits, what each does, and how components are combined to make working circuits in products.

A focused answer to OCR GCSE Design and Technology J310 on electronic components: resistors, capacitors, diodes and LEDs, transistors and integrated circuits, what each does and how they combine in circuits.

Generated by Claude Opus 4.89 min answer

Reviewed by: AI editorial process; not yet individually human-reviewed

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  1. What this dot point is asking
  2. The common components
  3. Input, process, output
  4. Combining components
  5. Try this

What this dot point is asking

OCR J310 treats electronic components as the sixth material category. You need to know the common components, what each does, and how they combine into working circuits in products. In the written exam this is tested by naming a component for a function and by explaining the roles of components in a simple circuit such as a sensing night light. It links directly to the electronic systems content in technical understanding.

The common components

Input, process, output

Mapping components to this structure makes circuits easy to reason about: an LDR or thermistor (input) feeds a transistor or microcontroller (process) that drives an LED, buzzer or motor (output). This is the same model used in the technical understanding topic.

Combining components

Components rarely work alone. A resistor and an LDR form a voltage divider that turns a change in light into a change in voltage; a transistor uses that voltage to switch an output; a series resistor protects the LED. Designers select and combine components so the circuit responds correctly and safely.

Try this

Q1. State what a diode does in a circuit. [1 mark]

  • Cue. Allows current to flow in one direction only.

Q2. Name the component used as an electronic switch in a sensing circuit. [1 mark]

  • Cue. A transistor.

Exam-style practice questions

Practice questions written in the style of OCR exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

OCR J310/01 20183 marksName the component that does each of the following: limits the current to protect an LED; allows current to flow in one direction only; stores electrical charge.
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A 3-mark question, one mark per correct component.

Limits current to protect an LED: a resistor (a current-limiting or series resistor). Allows current in one direction only: a diode. Stores electrical charge: a capacitor.

Markers reward the three correct components matched to their function. The LED point matters because an LED without a series resistor draws too much current and burns out, so the resistor protects it. A wrong match loses that mark.

OCR J310/01 20214 marksA night light should switch an LED on automatically when it gets dark. Explain the role of a sensor, a transistor and a resistor in this circuit.
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A 4-mark Explain wants the roles in a sensing circuit applied to the night light.

The sensor is a light-dependent resistor (LDR): its resistance rises as light falls, so it detects darkness (the input). A resistor is paired with the LDR to form a voltage divider, setting the voltage that decides the switching point, and another resistor limits the LED current. The transistor acts as an electronic switch: when the voltage from the divider rises enough (in the dark), the transistor turns on and lets current flow to switch the LED on (the output).

Markers reward: LDR senses darkness (input), the divider/resistor sets the threshold and protects the LED, and the transistor switches the LED on (process to output). A vague "the components make it work" caps the mark.

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