Question
- What is total internal reflection? Under what conditions does it occur?
- Find a relation between critical angle and refractive index.
- Name one phenomenon which is based on total internal reflection.
✓
Answer
- When a ray of light travels from a denser medium into a rarer medium at an angle greater than the critical angle, it reflects back into the denser medium. This phenomenon is called total internal reflection. Conditions for total internal reflection.
- Light should travel from denser medium to rarer medium.
- Angle of incidence should be greater than critical angle.
- $\frac{1}{\mu} = \frac{\sin\text{ i}}{\sin\text{ r}} , $ for total internal reflection to occur $i \geq i _{c}$ at critical angle, angle of refraction$\text{𝑟}=90^{o}$, hence, $\frac{1}{\mu} = \frac{\sin\text{i}_{c}}{\sin90^{o}}$
$\Rightarrow\mu = \frac{1}{\sin\text{i}_{c}}$
- Mirage/sparkling of diamond/ optical fiber/totally reflecting Prism/shinning of air bubbles in water.
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