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Alternating Current — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsAlternating Current3 Marks
Question
  1. What is total internal reflection? Under what conditions does it occur?
  2. Find a relation between critical angle and refractive index.
  3. Name one phenomenon which is based on total internal reflection.
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Answer

  1. 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.
    1. Light should travel from denser medium to rarer medium.
    2. Angle of incidence should be greater than critical angle.
  2. $\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, $\frac{1}{\mu} = \frac{\sin\text{i}_{c}}{\sin90^{o}}$

$\Rightarrow\mu = \frac{1}{\sin\text{i}_{c}}$

  1. Mirage/sparkling of diamond/ optical fiber/totally reflecting Prism/shinning of air bubbles in water.

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