Question

The distance between two slits is 1.2 mm. If the wavelength of light used is $4800\dot{A}$ and the screen is at a distance of 1 m from the slits, how many fringes are observed on the screen in the space opposite to the slits

• A. 1
• B. 2
• C. 3
• D. 8

Answer 1

The correct option is C 3

$y=\frac{d}{2};y=n\beta \Rightarrow \frac{d}{2}=n\frac{\lambda D}{d}$
$\Rightarrow n=1.5$ $\therefore$ the total fringes=3