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Subjects · Leaving Cert Physics

Leaving Cert Physics: Resistance

How often Resistance comes up on the Physics papers, every year it was asked, and questions to try.

HL Asked on 9 of the last 10 Higher Level papers, most recently in 2026. banker

OL Asked on 9 of the last 10 Ordinary Level papers, most recently in 2026. banker

June 2027 is the first exam on the new Physics course. These come from the 2016–2026 papers, so read them as a guide.

Resistance, Higher Level(7 marks)

Quick ones on Resistance.

(a)SI unit of resistance?
  1. Volt (V)
  2. Ohm (Ω)
  3. Watt (W)
(b)Resistance of a conductor carrying 3.0 A when 12 V is applied?
  1. 0.25 Ω
  2. 36 Ω
  3. 4.0 Ω
(c)What happens to the resistance of a metal wire as its temperature rises?
  1. It increases
  2. It does not change
  3. It decreases
Show the answers

(a) Ohm (Ω)

(b) 4.0 Ω

(c) It increases

Your turn: Higher Level questions on Resistance.

Higher Level

Asked on 9 of the last 10 Higher Level papers, most recently in 2026. banker

Every paper, year by year

YearWhere it came up
2026Q5
2025Q5, Q11
2024Q5
2023Q14(c)
2022Q6(i)
2021Q4
2019Q5(f)
2018Not asked
2017Q4, Q8
2016Q4

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

More Resistance questions

Resistance, 3 marks

State Ohm's law.

  1. At constant temperature the resistance of a conductor is directly proportional to the potential difference across it
  2. The current through a conductor is proportional to its resistance, whatever its temperature
  3. At constant temperature the current through a conductor is proportional to the potential difference across it
Show the answer

At constant temperature the current through a conductor is proportional to the potential difference across it

V = IR, which gives a straight line through the origin on a graph of V against I. The temperature must stay constant.

Resistance, 2 marks

SI unit of resistivity?

  1. Ω m²
  2. Ω m
  3. Ω m⁻¹
Show the answer

Ω m

ρ = RA ÷ l, so the units are Ω × m² ÷ m = Ω m (the ohm metre).

Resistance, 3 marks

A wire's diameter is doubled; its length and material are unchanged. Its resistance becomes?

  1. One quarter of the original
  2. One half of the original
  3. Four times the original
Show the answer

One quarter of the original

Area = πd²/4, so doubling d makes the area four times larger. R = ρl ÷ A, so the resistance falls to one quarter.

Ordinary Level

Asked on 9 of the last 10 Ordinary Level papers, most recently in 2026. banker

Every paper, year by year

YearWhere it came up
2026Q5
2025Q5
2024Q5, Q11
2023Q5, Q11
2022Q11
2021Q5, Q9
2019Q4, Q9
2018Q4, Q5(c)
2017Q4
2016Not asked

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

More Resistance questions

Resistance, 3 marks

Current through a 10 Ω resistor with 5 V across it?

  1. 2 A
  2. 50 A
  3. 0.5 A
Show the answer

0.5 A

V = IR, so I = V ÷ R = 5 ÷ 10 = 0.5 A. 2 A comes from dividing the wrong way; 50 A from multiplying.

Resistance, 2 marks

Unit of resistivity?

  1. Ohm (Ω)
  2. Ohm metre (Ω m)
  3. Ohm per metre (Ω m⁻¹)
Show the answer

Ohm metre (Ω m)

ρ = RA ÷ l. Ohms × square metres ÷ metres = ohm metres.

Resistance, 3 marks

Voltage needed to drive 2 A through a 6 Ω resistor?

  1. 12 V
  2. 3 V
  3. 8 V
Show the answer

12 V

V = IR = 2 × 6 = 12 V. 3 V comes from dividing; 8 V from adding.

Other Physics topics

All of Leaving Cert Physics