In the diffraction due to a single slit,the central fringe ...

Light appears to travel in straight lines since

In the diffraction pattern of a single slit,the width of the secondary maxima compared to the central maximum is:

If we observe the single slit Fraunhofer diffraction with wavelength $\lambda$ and slit width $e$,the width of the central maxima is $2\theta$. On decreasing the slit width for the same $\lambda$,what happens to $\theta$?

In an experiment, electrons are made to pass through a narrow slit of width '$d$' comparable to their de Broglie wavelength. They are detected on a screen at a distance '$D$' from the slit (see figure). Which of the following graphs can be expected to represent the number of electrons '$N$' detected as a function of the detector position '$y$' ($y = 0$ corresponds to the middle of the slit)?

For Bragg's diffraction by a crystal to occur,the $X$-ray of wavelength $\lambda$ and interatomic distance $d$ must satisfy which condition?