Minima in Diffraction

Q. In a double slit experiment, the distance between the slits is $d$. The screen is at a distance $D$ from the slits. If a bright fringe is formed exactly in front of one of the slits its order is,

1. $\frac{{\lambda }^2}{dD}$
   
2. $\frac{d}{\lambda }$
   
3. $\frac{d^2}{2D\lambda }$
   
4. $\frac{D^2}{2\lambda D}$
   

Q.

A circular hole of diameter 0.15 cm is placed 2.1 m from a screen. On illuminating it by light of wavelength $5\times {10}^{-7}m$ the width of central maxima will be

1. 70 mm

2. 0.171 mm

3. 1.71 mm

4. 1.4 mm

Q. Yellow light is used in single slit diffraction experiment with slit width 0.6 mm. If yellow light is replaced by X-rays then the pattern will reveal

[IIT-JEE (Screening) 1999; MP PMT 2002; KCET 2003]

1. That the central maxima is narrower

2. No diffraction pattern

3. More number of fringes

4. Less number of fringes

Q.

A diffraction is obtained by using a beam of red light. What will happen if the red light is replaced by the blue light

[KCET 2000; BHU 2001]

1. Bands will be narrower

2. Bands become broader and further apart

3. No change will take place

4. Bands disappear

Q.

The light of wavelength 6328 Å is incident on a slit of width 0.2 mm perpendicularly, the angular width of central maxima will be

[MP PMT 1987; Pb. PMT 2002]

1. 0.36°

2. 0.18°

3. 0.72°

4. 0.09°

Q. Light of the wavelength $550\text{nm}$ falls normally on a slit of width $22.0\times {10}^{-5}\text{cm}$. The angular position of the second minima from the central maxima will be :

1. $\frac{\pi }{8}$
2. $\frac{\pi }{12}$
3. $\frac{\pi }{6}$
4. $\frac{\pi }{4}$

Q.

A circular hole of diameter 0.15 cm is placed 2.1 m from a screen. On illuminating it by light of wavelength $5\times {10}^{-7}m$ the width of central maxima will be

1. 70 mm

2. 0.171 mm

3. 1.71 mm

4. 1.4 mm

Q. In a diffraction pattern due to a single slit of width a, the first minimum is observed at an angle ${30}^{\circ }$ when light of wavelength $5000\stackrel{\circ }{A}$ is incident on the slit. The first secondary maximum is observed at an angle of

1. $si{n}^{-1}\frac{2}{3}$
2. $si{n}^{-1}\frac{1}{2}$
3. $si{n}^{-1}\frac{3}{4}$
4. $si{n}^{-1}\frac{1}{4}$