# If the critical angle for total internal reflection from a medium to vacuum is 45°, then velocity of light

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If the critical angle for total internal reflection from a medium to vacuum is 45°, then velocity of light in the medium is :

(1) 3 × 108 m/s

(2) 1.5 × 108 m/s

(3) $3\over\sqrt2$ × 108 m/s

(4) $\sqrt2$ × 108 m/s