Optics Ques 53

  1. A ray of light travelling in water is incident on its surface open to air. The angle of incidence is $\theta$, which is less than the critical angle. Then there will be

(2007, 3M)

(a) only a reflected ray and no refracted ray

(b) only a refracted ray and no reflected ray

(c) a reflected ray and a refracted ray and the angle between them would be less than $180^{\circ}-2 \theta$

(d) a reflected ray and a refracted ray and the angle between them would be greater than $180^{\circ}-2 \theta$

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Answer:

Correct Answer: 53.(c)

Solution:

Formula:

Laws of Refraction (at any Refracting Surface):

  1. Since $\theta<\theta _c$, both reflection and refraction will take place. From the figure we can see that angle between reflected and refracted rays $\alpha$ is less than $180^{\circ}-2 \theta$.



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