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tt{Rays and wavefronts both indicate the direction of propagation of the electromagnetic wave, Rays are lines that are best for describing and studying waves in a 2D environment, whereas wavefronts are planes that are better used for 3D environments.}
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tt{Both describe the wave movement but are used for different analysis.}
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tt{Smooth surfaces produce clear images because all the reflected light is beamed in one direction, Refer to {color{#4257b2}{Figure16.4}} for an example.}
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tt{smooth surfaces}
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tt{The horizontal beamed light is reflected by a mirror at an angle $theta$, the angle of incidence(is the angle between the mirror surface and the normal to it) is then $90-theta.$

adding the angle of incidence, the angle of reflection, and $Phi$ form a $180^o$ degree angle geometrically, therefore:

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90-theta+90-theta+Phi=180 Rightarrow Phi=2theta
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if $thetauparrow$then$Phiuparrow$

$phi$ increase

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tt{if $theta=90^o$then the incident light hits the surface of the mirror with an angle $theta_i$ to the normal: }
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theta_i=90-theta=90-30=60^o
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theta_i=60^o
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tt{in {color{#4257b2}{Exercise 4}} we demonstrated through a geometrical analysis that $Phi=2theta$ }
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Rightarrow Phi=2*20=40^o
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tt{$Phi=40^o$}
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