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Subjects · Leaving Cert Physics & Chemistry

Leaving Cert Physics & Chemistry: Refraction

How often Refraction comes up on the Physics & Chemistry 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 6 of the last 9 Ordinary Level papers, most recently in 2025. most years

Refraction, Higher Level(7 marks)

Quick ones on Refraction.

(a)Snell's law: for light passing between two given media…
  1. i / r is constant
  2. sin i / sin r is constant
  3. i + r is always 90°
(b)A transparent material has refractive index 2.0. Its critical angle?
  1. 45°
  2. 60°
  3. 30°
(c)Total internal reflection needs light going from a denser to a less dense medium, and…
  1. An angle of incidence greater than the critical angle
  2. A silvered back surface to reflect all of the light
  3. An angle of incidence of 0°, along the normal
Show the answers

(a) sin i / sin r is constant

(b) 30°

(c) An angle of incidence greater than the critical angle

Your turn: Higher Level questions on Refraction.

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
2025Q3
2024Q6(a)
2023Q4
2022Q3
2021Q1(i), Q1(j)
2019Q4
2018Q3
2017Q1(d)
2016Q3

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

More Refraction questions

Refraction, 2 marks

Why does a swimming pool look shallower than it really is?

  1. Light is reflected off the surface of the water
  2. Water absorbs red light
  3. Light bends away from the normal as it leaves the water
Show the answer

Light bends away from the normal as it leaves the water

Rays from the bottom refract away from the normal at the surface. Your eye traces them back in straight lines to a point higher up, so the bottom appears raised.

Ordinary Level

Asked on 6 of the last 9 Ordinary Level papers, most recently in 2025. most years

Every paper, year by year

YearWhere it came up
2025Q1(g), Q1(i)
2024Q3
2023Not asked
2022Q3
2021Q1(j)
2019Not asked
2018Q3
2017Not asked
2016Q3

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

More Refraction questions

Refraction, 2 marks

Refraction of light is?

  1. Bouncing of light off a surface such as a mirror
  2. Spreading of light through a narrow gap or slit
  3. Bending of light passing from one medium to another
Show the answer

Bending of light passing from one medium to another

Light changes speed when it enters a new medium, so it changes direction. Bouncing is reflection; spreading through a gap is diffraction.

Refraction, 3 marks

Light enters glass with sin i = 0.6 and sin r = 0.4. Refractive index of the glass?

  1. 0.24
  2. 1.5
  3. 0.67
Show the answer

1.5

Snell's law: n = sin i ÷ sin r = 0.6 ÷ 0.4 = 1.5. The angle in air (i) goes on top, so n is bigger than 1.

Refraction, 2 marks

Total internal reflection can only happen when light travels?

  1. From a denser to a less dense medium
  2. From a less dense to a denser medium
  3. Along the normal
Show the answer

From a denser to a less dense medium

It needs light going from glass or water towards air, and an angle of incidence bigger than the critical angle.

Other Physics & Chemistry topics

All of Leaving Cert Physics & Chemistry