Refraction of light

A ray of light is incident on the surface of a glass block, as illustrated in the diagram below. The refractive index of the glass is $1.5$. As the light ray enters the glass, its direction changes. What is the angle $x$ through which the ray moves?

May/June 2015

A light ray moves from X to Y through an optical fibre. At Y, the angle of incidence is larger than the critical angle. In which direction does the light ray move after arriving at point Y?

May/June 2015

A light ray travelling in glass strikes the surface at angle $c$. Angle $c$ is the critical angle. Which diagram shows the path of the light?

May/June 2015

A ray of light strikes the surface of a glass block, as illustrated in the diagram below. The refractive index of the glass is $1.5$. As the light ray enters the glass, its direction changes. Through what angle $x$ does the ray deviate?

May/June 2015

Fig. 5.1 shows a ray of light as it enters an optical fibre and travels through it.

May/June 2015

A student is finding the refractive index of the glass in a semi-circular block. The student uses the relation refractive index $= \frac{\sin(\text{angle of incidence})}{\sin(\text{angle of refraction})}$. The semi-circular glass block is shown for you in Fig. 3.1. You may make drawings on Fig. 3.1.

May/June 2015

Light travels from air into a glass block with refractive index $1.5$, as illustrated. What is the angle of refraction in the glass and what is the critical angle?

May/June 2016

A ray of light travels from air into a glass block, as shown. Which expression gives the refractive index of the glass?

May/June 2016

Explain the meaning of critical angle.

May/June 2016

A student studies the route followed by a ray of light as it passes through a triangular prism.

May/June 2016

Light moving through glass strikes a glass-air boundary. The angle of incidence of the light is larger than the critical angle. Which arrow indicates the direction of the light after it strikes the boundary?

May/June 2017

A ray of light is incident on the upper face of a glass block at an angle of $15^\circ$ as illustrated. The refractive index of glass is $1.5$. What is the refraction angle $r$?

May/June 2017

Which device operates by total internal reflection?

May/June 2018

A student determines the refractive index $n$ of a rectangular glass block. Fig. 4.1 shows one face of the block. The student follows the route taken by a ray of light as it enters the block at side AB and leaves it at side CD.

May/June 2018

Fig. 3.1 illustrates three light rays moving through water from a light source S. At the water-air boundary, one of the rays is totally internally reflected.

May/June 2019

A student uses a ray box to examine how a ray of blue light is refracted as it passes through a glass prism. He arranges the apparatus as shown in Fig. 2.1 on a sheet of paper.

May/June 2019

As illustrated, light is refracted from a liquid into air. The refractive index for light travelling from air into the liquid is $1.4$. What is the angle of incidence in the liquid?

May/June 2021

A ray of red light travelling through air enters a semi-circular block. Which diagram shows both the partial reflection and the refraction of this ray?

May/June 2021

A beam of red light travelling in air enters a semi-circular block. Which diagram illustrates the ray’s partial reflection and refraction?

May/June 2021

A red light ray and a blue light ray, both travelling parallel, enter a glass prism.

May/June 2022

In Fig. 4.1, a ray of white light is incident on a glass prism. Because of refraction, the white light splits into different colours.

May/June 2022

A student sends two parallel light rays, ray 1 and ray 2, toward one side of a transparent plastic block, as shown in Fig. 3.1. The block is resting on a sheet of paper.

May/June 2022

A light ray strikes a plastic block in air with angle of incidence $i$. The plastic has refractive index $n$. When the ray reaches X, it is refracted along the plastic-air boundary. Which equation is correct?

May/June 2023

A light ray enters a block of transparent material, as illustrated. The angles marked are $35^\circ$ and $60^\circ$. What is the refractive index of the transparent material?

May/June 2023

The diagrams illustrate light travelling through a semi-circular glass block and then striking its straight edge. Which diagram represents refraction with an angle $i$ equal to the glass’s critical angle?

May/June 2023

Ultraviolet radiation forms one part of the electromagnetic spectrum.

May/June 2023

A light ray falls on the surface of a glass block with an angle of incidence of $45^\circ$. The refractive index of the glass is $1.8$. What is the angle of refraction inside the block?

May/June 2024

Fig. 4.1 illustrates a triangular glass prism with light travelling through it. The prism has points P, Q and R marked, and the rays entering and leaving the prism are shown.

May/June 2024

An underwater light illuminates a swimming pool. A ray of light strikes the water’s surface. What route does the ray of light take?

May/June 2025

A light ray travelling in glass strikes the surface at an angle $c$. Angle $c$ is the critical angle. Which diagram shows the effect on the light?

May/June 2025

A student studies how a ray of light is refracted as it travels through a transparent block and finds the block’s refractive index $n$. The student’s ray-trace sheet is shown at full size in Fig. 1.1. The transparent block’s outline is drawn as rectangle ABCD. A line SR that intersects side AD of the block is also marked.

May/June 2025

A light ray travelling in a transparent medium with refractive index $1.8$ strikes the surface as illustrated. The light passes into air. What is the angle between the refracted ray and the normal in air?

Oct/Nov 2015

At A, a light ray in air meets a parallel-sided glass block. The angle between the side of the block and the ray of light in air is $35^\circ$. The ray then reaches the block’s edge at B, and Fig. 7.1 shows the light ray together with the glass block. At A, the angle of refraction in the glass is $33^\circ$.

Oct/Nov 2015

A light ray strikes the surface of a glass block. The glass has refractive index $1.5$. The refraction angle is $r$. The angle between the refracted ray and the route the light would follow if the glass block were not present is $d$. What are $r$ and $d$?

Oct/Nov 2016

A lamp sits at the base of a shallow pool of water. The critical angle for light travelling from water into air is $49^\circ$.

Oct/Nov 2016

A laser emits a beam of red light.

Oct/Nov 2016

A solid plastic cylinder is placed in a liquid with refractive index $1.4$. Light in the plastic cylinder meets the inner surface at an angle of incidence of $70^{\circ}$. Total internal reflection occurs. What are the values of the critical angle in the plastic and the refractive index of the plastic?

Oct/Nov 2017

A beam of light is incident on a plastic block of refractive index $1.5$. The angle of incidence is $50^\circ$. What is the angle of refraction?

Oct/Nov 2017

A solid plastic cylinder is placed in a liquid with refractive index $1.4$. Light travelling in the plastic cylinder hits the inside surface at an angle of incidence of $70^\circ$. The light undergoes total internal reflection. Find the value of the critical angle in the plastic and the refractive index of the plastic.

Oct/Nov 2017

A student finds the refractive index of the material of a transparent block ABCD by following the route of a light ray through it. The setup is illustrated in Fig. 3.1.

Oct/Nov 2017

A student comes across the following statement in her physics book. “Here, the incident angle is more than $42^{\circ}$, the critical angle for glass in air.” What topic is the student reading about?

Oct/Nov 2018

Some waves are longitudinal, whereas other waves are transverse.

Oct/Nov 2018

The diagram illustrates a ray of light travelling in liquid and striking the boundary with air. Two further rays are seen. One remains in the liquid and the other lies in the air at the boundary. What is the angle of refraction?

Oct/Nov 2019

A beam of light is incident at $90^{\circ}$ on the surfaces of the two glass prisms P and Q. The critical angle for light travelling from glass into air is $42^{\circ}$. At which prism does total internal reflection occur?

Oct/Nov 2019

The diagram illustrates light travelling from glass into air. What is the name of angle $P$?

Oct/Nov 2019

A student studies how light is refracted by the right-angled glass prism WXY. He uses a ray box to send a beam of light towards side WY of the prism, as shown in Fig. 4.1.

Oct/Nov 2019

A light ray R strikes a surface from water to air at an incidence angle of $\theta$. The angle $\theta$ is smaller than the critical angle $c$. Which statement describes the path followed by R next?

Oct/Nov 2020

Which statement is correct about light travelling from air into glass?

Oct/Nov 2020

As illustrated in Fig. 4.1, the three angles of a glass prism are $45^\circ$, $45^\circ$ and $90^\circ$. At point Y, a ray of light with a single frequency travels through air and is incident on the prism face at $90^\circ$. The ray then enters the glass prism.

Oct/Nov 2020

A student uses a ray box to study how light travels through the transparent plastic block in Fig. 3.1.

Oct/Nov 2020

A student carries out an investigation into the reflection and refraction of light with a semi-circular glass block. • He puts a glass block on a sheet of paper. • He traces the outline of the block with a pencil. • He uses a ray box to send a ray of light to the centre C of the flat face AB of the block. • He marks AB and point C. Fig. 3.1 shows the observation made by the student. • He uses a pencil to put two crosses $X_1$ and $X_2$ on the incident ray. • He uses a pencil to put two crosses $X_3$ and $X_4$ on the emergent ray. • He uses a pencil to put two crosses $X_5$ and $X_6$ on the ray reflected from the face AB. • He removes the glass block and the ray box. Fig. 3.2 shows the student’s sheet of paper.

Oct/Nov 2020

A beam of light enters a glass block. It moves through the block and then leaves into the air. At the surface XY, which angle is the angle of refraction?

Oct/Nov 2021

Which example shows a transverse wave undergoing refraction?

Oct/Nov 2021

In Fig. 3.1, a beam of light enters a transparent block. It makes an angle $\theta$ with the normal as it enters, then passes through the block until it reaches the lower face. The angle between the ray inside the block and the block’s vertical side is $\phi$.

Oct/Nov 2021

A light ray travelling in water is refracted at the boundary into air. Which diagram indicates the angle of incidence $i$ and the angle of refraction $r$?

Oct/Nov 2022

A student is determining the refractive index of oil. The oil is poured into a semi-circular transparent plastic container, as illustrated in Fig. 1.1. The container is set on top of a $360^{\circ}$ protractor, as shown in Fig. 1.2.

Oct/Nov 2022

A student employs a ray box to explore how a ray of red light is refracted as it travels through a semi-circular glass block. He arranges the apparatus on a sheet of paper as shown in Fig. 3.1. The ray is incident at $M$, the mid-point of the flat surface of the semi-circular glass block.

Oct/Nov 2022

Light in air strikes a water surface. Water has a refractive index of $1.3$, and the angle of refraction in the water is $40^\circ$. What is the angle of incidence in air?

Oct/Nov 2023

The diagram illustrates a ray of light travelling through a triangular glass block. Which angle is the critical angle for light in glass?

Oct/Nov 2023

A narrow beam of red light, with frequency $4.7 \times 10^{14}\,\text{Hz}$, moves through air at a speed of $3.0 \times 10^8\,\text{m s}^{-1}$. Fig. 4.1 depicts this red light hitting the surface of a parallel-sided glass block. The diagram labels red light and glass block, and it shows angles $45^{\circ}$ and $30^{\circ}$.

Oct/Nov 2023

A ray of light travels from glass into air. Which arrow indicates the direction of the ray in the air?

Oct/Nov 2024

The diagram illustrates a ray of light moving from air into medium Q. What is the critical angle at the boundary between medium Q and air?

Oct/Nov 2024

A light ray moves from X to Y through an optical fibre. At Y, the angle of incidence is larger than the critical angle. In what direction does the light ray travel after it reaches point Y?

Oct/Nov 2025

Light enters a transparent substance with refractive index $n$. The angle of incidence at the surface of the transparent substance is $i$. Which equation is used to determine the angle of refraction $r$?

Oct/Nov 2025

Three light rays strike the surface separating a glass block and air, each with a different angle of incidence. What could be a possible critical angle for light in the glass?

Oct/Nov 2025

A student is studying how light refracts as it passes through a transparent block. Fig. 2.1 gives a plan view of the transparent block. The upper edge is marked X and Y, with point M on XY. Two crosses indicate the position of the emerging ray.

Oct/Nov 2025