Assume that light of wavelength 7000 $\stackrel{\mathrm{o}}{\mathrm{A}}$ is coming from a star. The limit of resolution (in radian) of a telescope whose objective has a diameter of 244 cm, will be

1.  $2.5 \times {10}^{-7}$

2.  $5.0 \times {10}^{-7}$

3.  $3.5 \times {10}^{-7}$

4.  $4.5 \times {10}^{-7}$

Light of wavelength 5000 $\stackrel{\mathrm{o}}{\mathrm{A}}$ travelling at a speed of $2 \times {10}^8$m/s in medium 1 is incident on a boundary and gets refracted into medium 2. Its wavelength after refraction is found to be 5500 $\stackrel{\mathrm{o}}{\mathrm{A}}$. Which of the following is incorrect?

1.  Refractive index of medium 2 is $\frac{11}{10}$.

2.  On entering medium 2, light bends away from normal.

3.  Speed of light is more in medium 2 than in medium 1.

4.  Its frequency remains unchanged.

Yellow light is used in a single slit diffraction pattern with a slit width of 0.5 mm. If the yellow light is replaced by X-rays, then the observed pattern will reveal

1.  No diffraction pattern

2.  More narrow central maximum

3.  More number of fringes

4.  Less number of fringes

In Young's double hole (slit) experiment using the light of wavelength 6000 $\stackrel{\mathrm{o}}{\mathrm{A}}$, the angular width of the fringe formed on a distant screen is $0.1°$. The slit separation is approximate:

1.  0.34 mm

2.  0.34 cm

3.  0.34 m

4.  0.034 mm

Intensity at the centre in YDSE is ${\mathrm{I}}_0$. If one of the slits is covered then, the intensity at the centre will be 

1.  ${\mathrm{I}}_0$

2.  2${\mathrm{I}}_0$

3.  ${\mathrm{I}}_0$/4

4.  ${\mathrm{I}}_0$/2

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

1.  Bands will become narrower

2.  Bands become broader

3.  No change will take place

4.  Bands disappear

When a thin transparent plate of thickness t and refractive index $\mu$ is placed in the path of one of the two interfering waves of light, then the extra path difference created between two waves due to the plate is

1.  $\left(\mu + 1\right)t$

2.  $\left(\mu - 1\right)t$

3.  $\left(\frac{\mu +1}{t}\right)$

4.  $\mu$t

If the ratio of amplitudes of two coherent sources producing an interference pattern is \(3:4\), the ratio of intensities at maxima and minima is:
1. \(3:4\)
2. \(9:16\)
3. \(49:1\)
4. \(25:7\)

In Young's double-slit experiment, the slit separation is made 3 fold. The fringe width becomes

1.  $\frac{1}{9}$ times

2.  $\frac{1}{3}$ times

3.  9 times

4.  3 times

Wavefront is:

1.  locus of all adjacent points at which the phase of vibration of a physical quantity associated with the wave in the same

2.  locus of all adjacent points at which the electric field is the same

3.  series of points on the wave with the same amplitude

4.  series of points on the wave with the same frequency