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Leaving Cert Engineering: Electronics & circuits

How often Electronics & circuits comes up on the Engineering papers, every year it was asked, and questions to try.

HL Asked on 7 of the last 9 Higher Level papers, most recently in 2025. most years

OL Asked on 9 of the last 9 Ordinary Level papers, most recently in 2025. banker

June 2028 is the first exam on the new Engineering course. These come from the 2016–2025 papers, so read them as a guide.

Electronics & circuits, Higher Level(7 marks)

Quick ones on Electronics & circuits.

(a)What happens to the resistance of an LDR in darkness?
  1. It falls to almost zero
  2. It rises greatly
  3. It stays the same
(b)A resistor's bands read brown, black, red, then gold. What is its value?
  1. 100 Ω
  2. 102 Ω
  3. 1 kΩ
(c)Which leg of an LED is the anode?
  1. The longer leg
  2. The leg by the flat edge
  3. The shorter leg
Show the answers

(a) It rises greatly

(b) 1 kΩ

(c) The longer leg

Your turn: Higher Level questions on Electronics & circuits.

Higher Level

Asked on 7 of the last 9 Higher Level papers, most recently in 2025. most years

Every paper, year by year

YearWhere it came up
2025Q1(b), Q1(k)
2024Q9(c)OR
2023Q1(k)
2022Q9(c)OR
2021Not asked
2019Q1(k), Q8(c)OR
2018Q8(c)OR
2017Q1(a), Q8(c)OR
2016Not asked

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

More Electronics & circuits questions

Electronics & circuits, 3 marks

Why use a relay in a control circuit?

  1. To store charge in its coil and release it later
  2. To convert the AC mains into a DC supply
  3. A small current can switch a separate, larger current
Show the answer

A small current can switch a separate, larger current

The coil forms an electromagnet that pulls the switch contacts over. A low-power circuit can safely control a motor or mains load, with the two circuits kept separate.

Electronics & circuits, 3 marks

Why is a resistor connected in series with an LED?

  1. To reverse the polarity if it is fitted backwards
  2. To limit the current so the LED does not burn out
  3. To make the LED flash on and off at a steady rate
Show the answer

To limit the current so the LED does not burn out

An LED has very low resistance once it conducts, so without a resistor the current would rise until it fails. The resistor drops the extra supply voltage.

Electronics & circuits, 2 marks

A PIR sensor detects?

  1. Infrared from warm moving bodies
  2. Sound echoes from moving bodies
  3. Magnetic fields from metal objects
Show the answer

Infrared from warm moving bodies

Passive infrared sensors notice a change in heat radiation as a person moves across their view. They are used in security lights and alarms.

Ordinary Level

Asked on 9 of the last 9 Ordinary Level papers, most recently in 2025. banker

Every paper, year by year

YearWhere it came up
2025Q1(c), Q7(c)OR
2024Q1(j), Q7(c)OR
2023Q7(c)OR
2022Q1(j), Q7(c)OR
2021Q1(h), Q7(c)OR
2019Q1(h), Q7(c)OR
2018Q1(f), Q1(l), Q7(c)OR
2017Q1(l), Q7(c)OR
2016Q7(c)OR

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

More Electronics & circuits questions

Electronics & circuits, 2 marks

In Ohm's law, V = IR, the letter I stands for?

  1. Voltage, in volts
  2. Resistance, in ohms
  3. Current, in amps
Show the answer

Current, in amps

V is voltage (volts), I is current (amps) and R is resistance (ohms). Current is written I from the French intensité.

Electronics & circuits, 3 marks

A 12 V supply drives a current of 0.4 A through a resistor. What is its resistance?

  1. 12.4 Ω
  2. 30 Ω
  3. 4.8 Ω
Show the answer

30 Ω

R = V ÷ I = 12 ÷ 0.4 = 30 Ω. Multiplying gives 4.8, which is the power in watts, not the resistance.

Electronics & circuits, 2 marks

Two 3.7 V cells are connected in series. Total voltage?

  1. 7.4 V
  2. 3.7 V
  3. 1.85 V
Show the answer

7.4 V

Cells in series add their voltages: 3.7 + 3.7 = 7.4 V. In parallel the voltage stays at 3.7 V but they last longer.

Other Engineering topics

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