Question

Two slits, $4mm$ apart, are illuminated by a light of wavelength $6000\mathring{A}.$ What will be the fringe width on a screen placed $2m$ from the slits?

• A. $0.12mm$
• B. $0.3mm$
• C. $3.0mm$
• D. $4.0mm$

Answer 1

The correct option is B $0.3mm$

Fringe width can be calculated as,

$\beta =\frac{\lambda D}{d}$

$=\frac{6000\times {10}^{-10}\times 2}{4\times {10}^{-3}}$

$=3\times {10}^{-4}m$

$=0.3mm$