Light waves: WAEC Physics Past Questions and Answers

What the WAEC syllabus covers in Light waves

Our summary: How light travels, reflects, refracts and disperses, and how mirrors, lenses and optical instruments work.

• Sources of light (Natural and artificial. Luminous and non-luminous bodies.)
• Rectilinear propagation of light (Formation of shadows and eclipse. Pinhole camera. Simple numerical problems may be set.)
• Reflection of light at plane surfaces: plane mirror (Regular and irregular reflections. Verification of laws of reflection. Formation of images. Inclined plane mirrors. Rotation of mirrors. Applications in periscope, sextant and kaleidoscope.)
• Reflection of light at curved surfaces: concave and convex mirrors (Laws of reflection. Formation of images. Characteristics of images. Use of mirror formulae $\frac{1}{u} + \frac{1}{v} = \frac{1}{f}$ and magnification $m = \frac{v}{u}$ to solve numerical problems. (Derivation of formulae is not required.) Experimental determination of the focal length of concave mirror. Applications in searchlight, parabolic and driving mirrors, car headlamps etc.)
• Refraction of light at plane surfaces: rectangular glass prism (block) and triangular prism (Laws of refraction. Formation of images, real and apparent depths. Critical angle and total internal reflection. Lateral displacement and angle of deviation. Use of minimum deviation equation: $\mu = \frac{\sin\frac{A + D_m}{2}}{\sin\frac{A}{2}}$.)
• Refraction of light at curved surfaces: converging and diverging lenses ((Derivation of the formula is not required.) Applications: periscope, prism binoculars, optical fibres. The mirage. Formation of images. Use of lens formulae $\frac{1}{u} + \frac{1}{v} = \frac{1}{f}$ and magnification $\frac{v}{u}$ to solve numerical problems (derivation of the formulae not required). Experimental determination of the focal length of converging lens. Power of lens in dioptres (D).)
• Application of lenses in optical instruments (Simple camera, the human eye, film projector, simple and compound microscopes, terrestrial and astronomical telescopes. Angular magnification. Prism binoculars. The structure and function of the camera and the human eye should be compared. Defects of the human eye and their corrections.)
• Dispersion of white light by a triangular glass prism (Production of pure spectrum of a white light. Recombination of the components of the spectrum. Colours of objects. Mixing coloured lights.)

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