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Subjects · Leaving Cert Computer Science

Leaving Cert Computer Science: Basic electronics

How often Basic electronics comes up on the Computer Science papers, every year it was asked, and questions to try.

HL Asked on 1 of the last 5 Higher Level papers, most recently in 2022.

OL Asked on 2 of the last 5 Ordinary Level papers, most recently in 2024.

Basic electronics, Higher Level(7 marks)

Quick ones on Basic electronics.

(a)Which component acts as a tiny electronic switch and is the building block of CPUs?
  1. Capacitor
  2. Transistor
  3. Resistor
(b)Which component stores electric charge?
  1. Diode
  2. Resistor
  3. Capacitor
(c)Why is a resistor placed in series with an LED?
  1. To limit the current so the LED is not damaged
  2. To make the LED flash on and off at a steady rate
  3. To store charge so the LED stays lit longer
Show the answers

(a) Transistor

(b) Capacitor

(c) To limit the current so the LED is not damaged

Your turn: Higher Level questions on Basic electronics.

Higher Level

Asked on 1 of the last 5 Higher Level papers, most recently in 2022.

Every paper, year by year

YearWhere it came up
2025Not asked
2024Not asked
2023Not asked
2022A3
2021Not asked

Links open the State Examinations Commission’s paper for that year.

More Basic electronics questions

Basic electronics, 2 marks

What does LED stand for?

  1. Low-energy display
  2. Light electric detector
  3. Light-emitting diode
Show the answer

Light-emitting diode

An LED gives out light when current flows through it the right way. It needs a resistor in series to limit that current.

Basic electronics, 2 marks

What does a diode do in a circuit?

  1. Increases the voltage across the circuit
  2. Lets current flow in one direction only
  3. Stores electric charge until it is needed
Show the answer

Lets current flow in one direction only

A diode blocks current in the reverse direction. An LED is a diode that also gives out light, so it only lights when fitted the right way round.

Ordinary Level

Asked on 2 of the last 5 Ordinary Level papers, most recently in 2024.

Every paper, year by year

YearWhere it came up
2025Not asked
2024A3
2023Not asked
2022A10
2021Not asked

Links open the State Examinations Commission’s paper for that year.

More Basic electronics questions

Basic electronics, 2 marks

Which component limits the flow of current in a circuit?

  1. Capacitor
  2. Transistor
  3. Resistor
Show the answer

Resistor

A resistor reduces current to protect other parts. Its value is measured in ohms and shown by coloured bands.

Basic electronics, 2 marks

Which component acts as a tiny electronic switch inside a chip?

  1. Capacitor
  2. Transistor
  3. Resistor
Show the answer

Transistor

A transistor switches on (1) or off (0). Billions of them are combined into logic gates inside a CPU.

Basic electronics, 3 marks

Why is a resistor connected in series with an LED?

  1. To limit the current and protect the LED
  2. To store charge so the LED stays on longer
  3. To make the LED flash on and off
Show the answer

To limit the current and protect the LED

Too much current burns out an LED. The resistor limits the current. Flashing is done by the program switching the LED on and off.

Other Computer Science topics

All of Leaving Cert Computer Science