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Is there actually any evidence that being in water increases your risk of getting sunburn? I suspect that this inference confuses correlation with cause. On brilliant sunny days you are more likely to strip off and get in the pool or go to the beach to cool down. If swimming or diving you are unlikely to wear a sunhat. More of your skin (especially the ...


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Yes. It's is not so much the water is the beach sand reflecting light back to you like a parabolic mirror. The droplets of water on your skin can form more surface area to catch light creating a magnifying effect focusing light on your skin as well. The random texture in the beach sand will also give you even tan. Most sand is white in color even if not the ...


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When you see a rainbow is when the incoming white light comes from a very small bright source, like when the sky is very clear in one direction and the sun shines in from that direction to the rain under the clouds on the opposite side from where you are looking. If the light source is diffuse, then you get lots of rainbows all jumbled together into uniform ...


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Light is multiply scattered in clouds, i.e. it is refracted by one water droplet or ice crystal, then refracted again by the next, then again by the next and so on. By the time the light reaches you eyes it will have been scattered many times. This means all the light hitting the cloud gets thoroughly mixed up and all the rainbows are jumbled up together and ...


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As John stated, the relation is not constant. Where does the need to "show that $\frac{i}{r}$ is constant come from? You know that if $i=0\rightarrow r=0$. You know that $$n_i\sin{i}=n_r\sin{r}$$ From this you should be able to see clearly that there's no linear relation except when $i$ approaches $0$, or $n_r$ approaches $n_i$. You should never go into ...


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For an intuitive answer to your first question, please see both my answer and and that of @theSkinEffect about the Effective Refractive Index. However, a more complete answer concerning the modes of a fiber is found in these lecture notes. For your second question, what is the dimensions of the waveguide (i.e. diameter)? What is the wavelength of interest? ...


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The refractive index of a material, $n$, is the ratio of the speed of light in vacuum and the speed of light in a given bulk media for given frequency. Thus, you could say that $refractive \space index = n(\omega, \epsilon_r, \mu_r) = \frac{c}{v}= \frac{\frac{1}{\sqrt{\epsilon_0 \mu_0}}}{\frac{1}{\sqrt{\epsilon(\omega) \mu(\omega)}}}= \frac{\sqrt{\epsilon(\...


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Total Internal Reflection is an example of reflection. In TIR and other forms of reflection (e.g. reflection off of a mirror or other barrier) the angle of incidence will be equal to the angle or reflection. You wrote "TIR reflects with the angle of incidence=angle of refraction." I'm not sure if this is a typo or if this is what you intended but "...


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Using Snell's law when light travels from glass to air, $$ 1.5\sin(i) = sin(r)$$ If $\sin(i)=2/3$ then the refracted ray grazes the surface as $r=90^o$. If the value of $i$ is greater than this value, total internal reflection (TIR) takes place. For any $i$ greater than around $42^o$ in glass to air interface TIR would take place.


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It's a poorly written question. As you have discovered, a ray incident on the glass side of the interface at 60° to the normal would be totally internally reflected and there would be no transmitted ray. Well, not unless it's glass with an unusually low refractive index. It's possible there is a misprint and they mean the angle is 60° to the surface i.e. 30°...



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