In Young's experiment, the wavelength of red light is 7.8× 10- 8 cm and that of blue light is 5.2× 10- 8 cm . Value of n for which (n+1 )th blue bright fringe coincides with nth red fringe is

Question

In Young's experiment, the wavelength of red light is 7.8× 10- 8 cm and that of blue light is 5.2× 10- 8 cm . Value of n for which (n+1 )th blue bright fringe coincides with nth red fringe is (A) 1 (B) 2 (C) 3 (D) 4

Tardigrade Admin · Accepted Answer

As we know that n1 λ 1=n2 λ 2 ∴ (n2/n1)=(λ 1/λ 2)=(7.8 × 10- 8/5.2 × 10- 8)=(3/2) Also n2-n1=1 ∴ n1=2

Q. In Young's experiment, the wavelength of red light is $7.8 \times 1 0^{- 8} c m$ and that of blue light is $5.2 \times 1 0^{- 8} c m$ . Value of n for which $(n + 1)^{t h}$ blue bright fringe coincides with $n^{t h}$ red fringe is

$1$

$2$

$3$

$4$

As we know that $n_{1} λ_{1} = n_{2} λ_{2}$
$∴ \frac{n _{2}}{n _{1}} = \frac{λ _{1}}{λ _{2}} = \frac{7.8 \times 1 0 ^{- 8}}{5.2 \times 1 0 ^{- 8}} = \frac{3}{2}$
Also $n_{2} - n_{1} = 1$
$∴ n_{1} = 2$

Q. In Young's experiment, the wavelength of red light is 7.8×10−8cm and that of blue light is 5.2×10−8cm . Value of n for which (n+1)th blue bright fringe coincides with nth red fringe is

1

2

3

4

As we know that n1​λ1​=n2​λ2​ ∴n1​n2​​=λ2​λ1​​=5.2×10−87.8×10−8​=23​ Also n2​−n1​=1 ∴n1​=2

Q. In Young's experiment, the wavelength of red light is $7.8 \times 1 0^{- 8} c m$ and that of blue light is $5.2 \times 1 0^{- 8} c m$ . Value of n for which $(n + 1)^{t h}$ blue bright fringe coincides with $n^{t h}$ red fringe is

$1$

$2$

$3$

$4$

As we know that $n_{1} λ_{1} = n_{2} λ_{2}$
$∴ \frac{n _{2}}{n _{1}} = \frac{λ _{1}}{λ _{2}} = \frac{7.8 \times 1 0 ^{- 8}}{5.2 \times 1 0 ^{- 8}} = \frac{3}{2}$
Also $n_{2} - n_{1} = 1$
$∴ n_{1} = 2$