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Leaving Cert Technology: Electronic components & circuits

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

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

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

Electronic components & circuits, Higher Level(7 marks)

Quick ones on Electronic components & circuits.

(a)As more light falls on an LDR, its resistance:
  1. Increases
  2. Decreases
  3. Stays the same
(b)Two transistors with gains of 100 and 50 form a Darlington pair. What is the overall gain?
  1. 2
  2. 150
  3. 5000
(c)Why must an electrolytic capacitor be fitted the right way round?
  1. It is polarised and can fail if reversed
  2. It works only on mains a.c. supplies
  3. It is non-polarised, but its value drops if reversed
Show the answers

(a) Decreases

(b) 5000

(c) It is polarised and can fail if reversed

Your turn: Higher Level questions on Electronic components & circuits.

Higher Level

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

Every paper, year by year

YearWhere it came up
2025A4, B2a, B2b
2024A3, A4
2023A4, B3b, B3c
2022B2b, B3b, B3c
2021A9, B3b
2019A6, B2b, B3c, B3d
2018A2, B2d
2017A3, A4, B3a
2016B2c

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

More Electronic components & circuits questions

Electronic components & circuits, 3 marks

An LDR is the top resistor of a divider feeding a transistor's base. When does the transistor turn on?

  1. When it gets dark
  2. When it gets hot
  3. When it gets light
Show the answer

When it gets light

Light lowers the LDR's resistance, so more voltage appears across the bottom resistor at the base. Above about 0.7 V the transistor turns on. Swap them for a dark sensor.

Electronic components & circuits, 3 marks

An LED will not light, but a meter shows the full supply voltage across it. What is the most likely fault?

  1. The series resistor is open circuit
  2. The LED is reversed or open circuit
  3. The battery is flat
Show the answer

The LED is reversed or open circuit

No current flows, so the resistor drops no voltage and the whole supply appears across the LED. A flat battery or a broken resistor would give about 0 V across the LED.

Electronic components & circuits, 2 marks

As an NTC thermistor gets hotter, its resistance:

  1. Decreases
  2. Increases
  3. Stays the same
Show the answer

Decreases

NTC means negative temperature coefficient: resistance falls as temperature rises. In a potential divider this changes the voltage, which can switch a transistor.

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
2025A9
2024A4, B3b
2023A8, B3b
2022B2b
2021B2b
2019A11, B2b
2018A4, B3b
2017A4, B3b
2016A4, A8, B2b

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

More Electronic components & circuits questions

Electronic components & circuits, 2 marks

What happens to the resistance of an LDR as the light gets brighter?

  1. It increases
  2. It stays the same
  3. It decreases
Show the answer

It decreases

A light dependent resistor has high resistance in the dark and low resistance in bright light, so it is used as a light sensor, e.g. in automatic night lights.

Electronic components & circuits, 2 marks

In a three-pin plug, what colour is the live wire?

  1. Green and yellow
  2. Brown
  3. Blue
Show the answer

Brown

Brown is live and goes to the fuse, blue is neutral and green/yellow is earth. The fuse melts if too much current flows, protecting the flex from overheating.

Electronic components & circuits, 2 marks

A thermistor is used to sense…

  1. Temperature
  2. Light
  3. Moisture
Show the answer

Temperature

A thermistor's resistance changes with temperature. Common NTC types have lower resistance when hot and are used in thermostats, fire alarms and fridges.

Other Technology topics

All of Leaving Cert Technology