A parallel beam of moving electrons is incident normal on a narrow slit. A fluorescent screen is placed at a large distance from the slit. If the slit is further narrowed, then which of the following statements is correct?

1.	The diffraction pattern is not observed on the screen in the case of electrons.
2.	The angular width of the central maximum of the diffraction pattern will increase.
3.	The angular width of the central maximum will decrease.
4.	The angular width of the central maximum will remain the same.

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

By Huygen's wave theory of light, we cannot explain the phenomenon of:

Soap bubble appears coloured due to the phenomenon of:
1. Interference
2. Diffraction
3. Dispersion
4. Reflection

Which of the following statements indicates that light waves are transverse? 

If an interference pattern has maximum and minimum intensities in a \(36:1\) ratio, then what will be the ratio of their amplitudes?
1. \(5:7\)
2. \(7:4\)
3. \(4:7\)
4. \(7:5\)

In Young's experiment, light of wavelength \(4000~\mathring{A}\) is used to produce bright fringes of width \(0.6\) mm, at a distance of \(2\) meters. If the whole apparatus is dipped in a liquid of refractive index \(1.5\), then fringe width will be:
1. \(0.2~\text{mm}\)
2. \(0.3~\text{mm}\)
3. \(0.4~\text{mm}\)
4. \(1.2~\text{mm}\)

In two separate set-ups of the Young's double slit experiment, fringes of equal width are observed when lights of wavelengths in the ratio \(1:2\) are used. If the ratio of the slit separation in the two cases is \(2:1\), the ratio of the distances between the plane of the slits and the screen in the two set-ups is:
1. \(4:1\)
2. \(1:1\)
3. \(1:4\)
4. \(2:1\)

The slits in Young's double-slit experiment have equal widths and the source is placed symmetrically relative to the slits. The intensity at the central fringe is \(I_0\). If one of the slits is closed, the intensity at this point will be:
1. \(I_0\)
2. \(\frac{I_0}{4}\)
3. \(\frac{I_0}{2}\)
4. \(4I_0\)