Free Download of Jamb-UTME-Physics past questions with Answers on "Light and its Reflection."
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 the studying of this subject.
Side Note: 'ume 91@04' in the pack implies ume 1991 question number 4.
As the motto of the website says-understanding what you know is the key-therefore, I'd like to explain briefly this topic.
Brief explanation on the topic
Straight-line Propagation of Light
Luminous and non-luminous objects
The subject of optics or light deals with luminous energy, that is, energy which causes the sensation of vision. The sun and the stars are self-luminous objects. Some living creatures such as the glow-worm or fire-fly are also self-luminous; they give out light themselves. Examples of artificial or man-made luminous sources are the electric lamp and the candle.
By contrast, the pages of this book are non-luminous. If you are reading it in daylight, light from the sun is falling on the page and some of it is scattered or reflected back to your eyes by the white page. The black print absorbs the light and stands out on the page. Similarly, light from an electric lamp is reflected back to your eyes if you are reading at night. A car driver at night can see a 'Stop' sign, or the rear reflector of a bicycle, by light reflected back from the car headlamps. Most objects are non-luminous. A person's face, or the pattern on a tie, for example, is seen by the sun or artificial light falling on it which is reflected back.
Rays of light
The direction or path along which light energy travels is called a light ray. The lines shown in the Fig. below (a) are rays which spread outwards from a very small lamp or 'point source' of light.
A collection or beam of rays which spreads-outwards as shown in Fig. (a) is called a divergent beam. A parallel beam is shown in Fig. (b). A convergent beam is shown in Fig. (c).
For demonstration purposes, narrow beams or 'rays' of light are conveniently obtained from a ray-box B shown in the figure below. This has a small filament lamp L in an enclosed box, a cylindrical converging lens C and a comb' S containing parallel slits in front of the lens. By moving the lamp L, a diverging, parallel or converging beam of rays can easily be obtained.
Light and large apertures
If a ray-box is placed on a sheet of white paper and switched on, a thick ray is obtained through each of the rectangular slits of the 'comb' as shown in the figure above. This so-called ray is actually a very narrow beam of light. The edges of the ray are well defined, and so the light can be seen to be travelling in straight lines. We call this the 'rectilinear propagation' of light. With a much-wider opening, such as an open letter-box or a window, sunlight can be seen streaming through by light scattered from dust particles. The edges of the wide beam are again straight, showing that light travels in straight lines.
The rectilinear propagation of light can be demonstrated by placing an illuminated lamp L in front of a hole A in a piece of cardboard, and then moving two other pieces of cardboard, with holes B and C, until the light through A can be seen- as shown in the figure below. A thread passing through A, B and C and pulled tightly is perfectly straight along ABC, showing that the three holes are in a straight line.
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