$A$ parallel beam of fast-moving electrons is incident normally on a narrow slit. $A$ fluorescent screen is placed at a large distance from the slit. If the speed of the electrons is increased,which of the following statements is correct?

Angular width of the central maximum of a diffraction pattern due to a single slit does not depend upon:

$A$ single slit diffraction experiment is performed to determine the slit width using the equation,$\frac{b d}{D} = m \lambda$,where $b$ is the slit width,$D$ is the distance between the slit and the screen,$d$ is the distance between the $m^{\text{th}}$ diffraction maximum and the central maximum,and $\lambda$ is the wavelength. $D$ and $d$ are measured with scales of least count of $1 \ cm$ and $1 \ mm$,respectively. The values of $\lambda$ and $m$ are known precisely to be $600 \ nm$ and $3$,respectively. The absolute error (in $\mu m$) in the value of $b$ estimated using the diffraction maximum that occurs for $m=3$ with $d=5 \ mm$ and $D=1 \ m$ is $.....$

The angular width of the central maximum in a single-slit diffraction pattern does not depend on .........

The main difference in the phenomenon of interference and diffraction in light waves is that

In a single slit diffraction pattern,the wavelength of light used is $628 \text{ nm}$ and slit width is $0.2 \text{ mm}$. The angular width of the central maximum is $\alpha \times 10^{-2} \text{ degrees}$. The value of $\alpha$ is . . . . . . . (Take $\pi = 3.14$)