Question

A biprism is placed at a distance of 50 mm in front of a narrow slit illuminated by light of wavelength 600 nm . The virtual images formed by the biprism are 0.5 mm apart . Find the width of the fringes formed on a screen placed 0.75 m apart in front of the biprism.

• A. 0.96 cm
• B. 0.096 cm
• C. 0.0096 cm
• D. 9.6 cm

Answer 1

The correct option is B 0.096 cm

for a fresnal biprism,

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

$given,\lambda =600nm;d=0.5mm;D=(750+50)=800mm;$

$\therefore \beta =\frac{600nm\times 800mm}{0.5mm}=0.096cm....\left(answer\right)$