Question 245: Waves Optics

Question

In Fraunhofer diffraction pattern, slit width is 0.3 mm and screen is at 1.5 m away from the lens. If wavelength of light used is $4500 \mathop {m{A}}\limits^{m{o}}$, then the distance between the first minimum on either side of the central maximum is [ $	heta$ is small and measured in radian.]

Accepted Answer

Distance of $1^{	ext {st }}$ minima from central maxima
$$ y_{1 d}=\frac{\lambda D}{a} $$
Distance between two minima on either side of the central maxima is
$$ 2 \mathrm{y}_{1 \mathrm{~d}}=\frac{2 \lambda \mathrm{D}}{\mathrm{a}}=\frac{2 	imes 4500 	imes 10^{-10} 	imes 1.5}{0.3 	imes 10^{-3}}=4.5 \mathrm{~mm} $$

Answer

1.5 mm

Answer

2.25 mm

Answer

3.25 mm

Answer

4.5 mm

Waves Optics

In Fraunhofer diffraction pattern, slit width is 0.3 mm and screen is at 1.5 m away from the lens. If wavelength of light used is 4500 \mathop {\rm{A}}\limits^{\rm{o}}, then the distance between the first minimum on either side of the central maximum is [ \theta is small and measured in radian.]

Choose the correct answer: