Free Download of Jamb's Utme Physics past questions with Answers on "Refraction of Light."

There have been lots of posts out there, stating 'Free Download of  UTME Physics past questions with Answers' but only questions without answers. This has prompted me to painstakingly create this pack by solving Jamb physics past questions on different topics and making them available to download for free. Not only are these questions solved topics by topics, they're also solved systematically from the simplest to the hardest. It is a unique past questions pack with answers to make easy studying of the subject.

Side Note: 'ume 91@04' in the pack implies ume 1991 question number 4.
As the description of the website displays-understanding what you know is the key- I would like to explain this topic briefly.

Brief explanation on the topic

Refraction at Plane Surfaces

As shown in the figure above, the bottom of a swimming pool appears to be nearer the surface than it really is. Also, letters in print seem to be nearer when a thick block of glass is placed over them- fig. (b). This is due to a change in direction of light when it travels from water or glass into air. The phenomenon is called refraction. Refraction occurs when light travels from air into a glass lens.

Refraction through rectangular block and prism

The refraction of rays of light from air to glass or from glass to air can be investigated with a ray-box. A parallel beam of light from the box R is incident on a rectangular glass block ABCD as shown in the figure (a) above. When the rays are normal, i.e. at 90°, to the side AB, they pass through the glass and come out without change of direction. In this case we can see no refraction. But when the ray-box is turned so that the light rays meet the glass surface at an acute angle, say 60°, there is a noticeable change. The beam inside the glass now travel, in a different direction XZ-fig (b). Refraction has taken place. The light beam comes out into the air at Z in the same direction as the incident beam at X, but is displaced sideways.
Glass prisms are used in optics. Fig. (c) shows that the beam refracted by a triangular glass prism PQS comes out or emerges in a completely different direction to the incident beam. So the incident light is deviated by the prism. Refraction through water can be seen by placing a little fluorescein in a rectangular tank of water. The change of direction of the ray when a beam enters the back face of the tank is then clearly visible.

Rules for refraction at boundaries

In the figure above, when a ray PA is incident in air on the air-glass boundary, it is refracted towards the normal NAM when it enters the glass. Some of the light is also reflected at A along AS but AS is a weak ray compared with the refracted ray. We also see that the ray AB in glass is refracted at the glass-air boundary along BQ in air, away from the normal at B. Similar results are obtained at an air-water boundary and a water-air boundary.
Generally, you should remember that Light travelling from one medium such as air to an optically denser medium such as glass or water is refracted towards the normal. When travelling from glass or water to a less dense medium such as air, the light is refracted away from the normal.

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