The time required for the light to pass through a glass slab (refractive index = 1.5) of thickness 4 mm is (c = 3 × 108 ms-1, speed of light in free space).

Question

The time required for the light to pass through a glass slab (refractive index = 1.5) of thickness 4 mm is (c = 3 × 108 ms-1, speed of light in free space). (A) 10-11 sec (B) 2×10-11 sec (C) 2×10+11 sec (D) 2×10-5 sec

Tardigrade Admin · Accepted Answer

We know, na ca=ng cg (ng/na)=(ca/cg) (3/2)=(3 × 108/cg) cg=2 × 108 We have,Time =( text Distance / text Speed ) t=(4 × 10-3/2 × 108) Or t=2 × 10-11 s

Q. The time required for the light to pass through a glass slab (refractive index = $1.5$ ) of thickness $4 mm$ is ( $c = 3 \times 1 0^{8} m s^{- 1}$ , speed of light in free space).

$1 0^{- 11} sec$

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

$2 \times 1 0^{+ 11} sec$

$2 \times 1 0^{- 5} sec$

We know,
$n_{a} c_{a} = n_{g} c_{g}$
$\frac{n _{g}}{n _{a}} = \frac{c _{a}}{c _{g}}$
$\frac{3}{2} = \frac{3 \times 1 0 ^{8}}{c _{g}}$
$c_{g} = 2 \times 1 0^{8}$
We have,Time $= \frac{Distance}{Speed}$
$t = \frac{4 \times 1 0 ^{- 3}}{2 \times 1 0 ^{8}}$
Or $t = 2 \times 1 0^{- 11} s$

Q. The time required for the light to pass through a glass slab (refractive index = 1.5) of thickness 4mm is (c=3×108ms−1, speed of light in free space).

10−11sec

2×10−11sec

2×10+11sec

2×10−5sec