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A thin prism of angle 15° made of glass of refractive index µ1 = 1.5 is combined with another prism of glass of refractive index µ2 = 1.75. The combination of the prism produces dispersion without deviation. The angle of the second prism should be
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- 7°
- 10°
- 12°
- 5°
Correct Option: B
Deviation = zero
So, δ = δ1 + δ2 = 0
⇒ (µ1 – 1)A1 + (µ2 – 1) A2 = 0
⇒ A2 (1.75 – 1) = – (1.5 – 1) 15°
| ⇒ A2 = | × 15° | |
| 0.75 |
or A2 = – 10°.
Negative sign shows that the second prism is inverted with respect to the first.
