A) \[1.1\,\text{eV}\]
B) \[1.5\,\text{eV}\]
C) \[2.0\,\text{eV}\]
D) \[\text{1}0.\text{2 eV}\]
Correct Answer: C
Solution :
Key Idea: Since angle of incidence is greater than angle of refraction ray of light bends towards the normal. When a ray of light travels from a rarer to a denser medium it bends towards the normal. From Snell?s law Where \[\mu \] is refractive index of the medium, \[i\]is angle of incidence and \[r\] is angle of refraction. Given, \[i={{45}^{\circ }}\], \[r={{30}^{\circ }}\] \[\therefore \] \[\mu =\frac{\sin \,\,{{45}^{\circ }}}{\sin \,\,{{30}^{\circ }}}=\frac{1}{\sqrt{2}}\times 2\] Also \[\mu =\frac{\text{velocity in air vacuum}}{\text{velocity in medium}}=\frac{3\times {{10}^{8}}}{{{v}_{m}}}\] \[\Rightarrow \] \[{{v}_{m}}=\frac{3\times {{10}^{8}}}{1.414}=2.12\times {{10}^{8}}\,\,m/s\] Note: Velocity of light is less in the denser medium, compared to rarer medium.You need to login to perform this action.
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