Question

The Slits in Young’s double slit experiment are illuminated by light of wavelength 6000 Å. If the path difference at the central bright fringe is zero, what is the path difference for light from the slits at the fourth bright fringe?

• A. 2.4×10^-6m
• B. 1.2×10^-6m
• C. 10^-6m
• D. 0.5×10^-6m

Answer 1

Answer: (A)

2.4×10^-6m

Answer 2

: The path difference at the centre is zero. The path difference at the $4^{th}$ bright fringe$= 4\lambda$

Hence $\lambda = 6000 \times 10^{- 10}m$

$\therefore$Path difference

$= 4 \times 6000 \times 10^{- 10} = 24 \times 10^{- 7}$

$= 2.4 \times 10^{- 6}m$