Refraction through a prism
- A light ray enters through a right angled prism at point P with the angle of incidence 30^° as shown in figure. It travels through the prism parallel to its base BC and emerges along the face AC. The refractive index of the prism is: Answer: 3. sqrt5/2 Key idea: The ray leaves along face AC, so its angle of incidence on AC is the critical angle C , with sin C=frac1μ . Let... 1
- Find the value of the angle of emergence from the prism. Refractive index of the glass is √(3). Answer: 1. 60^° Key idea: a ray hitting a face along its normal goes straight in; then apply Snell's law at the next face. The ray enters th... 1
- A ray is incident at an angle of incidence i on one surface of a small angle prism (with angle of prism A) and emerges normally from the opposite surface. If the refractive index of the material of the prism is μ, then the angle of incidence is nearl… Answer: 3. μ A For a small-angle prism, with emergent ray normal to the second face, the angle of refraction at the second face is 0. Since... 1
- The refractive index of the material of a prism is 2 and the angle of the prism is 30^°. One of the two refracting surfaces of the prism is made a mirror inwards, by silver coating. A beam of monochromatic light entering the prism from the other face… Answer: 3. 45^° The ray retraces its path only if it strikes the silvered face normally. The prism angle is A=30^° . For a ray hitting the s... 1
- A thin prism having refracting angle 10^° is made of glass of refractive index 1.42. This prism is combined with another thin prism of glass of refractive index 1.7. This combination produces dispersion without deviation. The refracting angle of seco… Answer: 1. 6 ^° Key idea: dispersion without deviation means the net deviation is zero: (μ₁-1)A₁=(μ₂-1)A₂ . (1.42-1)×10=(1.7-1)A₂⇒ 4.2=0.7A₂... 1
- The angle of incidence for a ray of light at a refracting surface of a prism is 45^°. The angle of prism is 60^°. If the ray suffers minimum deviation through the prism, the angle of minimum deviation and refractive index of the material of the prism… Answer: 2. 30^°;\ √(2) Key idea: at minimum deviation the ray passes symmetrically, so r₁=r₂=A/2 and i=A+δ_m/2 . r=30^° ; μ=sin45^°/sin30^°=... 1