Time taken by light to cross a glass slab of thickness 4 mm and refractive index 3, is

Question

Time taken by light to cross a glass slab of thickness 4 mm and refractive index 3, is (A)  4× 10-11s  (B)  2× 10-11s  (C)  16× 10-11s  (D)  8× 10-11s

Tardigrade Admin · Accepted Answer

Using the relation Time taken =( text distance / text velocity ) =( text optical path / text velocity of light ) i.e. t=(μ t/c)=(3 × 4 × 10-3/3 × 108) =4 × 10-11 sec

Q. Time taken by light to cross a glass slab of thickness $4 mm$ and refractive index $3$ , is

$4 \times 1 0^{- 11} s$

$2 \times 1 0^{- 11} s$

$16 \times 1 0^{- 11} s$

$8 \times 1 0^{- 11} s$

Using the relation
Time taken $= \frac{distance}{velocity}$
$= \frac{optical path}{velocity of light}$
i.e. $t = \frac{μ t}{c} = \frac{3 \times 4 \times 1 0 ^{- 3}}{3 \times 1 0 ^{8}}$
$= 4 \times 1 0^{- 11} sec$

Q. Time taken by light to cross a glass slab of thickness 4mm and refractive index 3, is

4×10−11s

2×10−11s

16×10−11s

8×10−11s