41.

Two slits in  Young's experiment have widths in the ratio 1:25.The ratio of intensity at the maxima and minima in the interference pattern I_max/I_min is

• 9/4

• 121/49

• 49/121

• 49/121

In an astronomical telescope in normal adjustment, a straight black line of length L is drawn on inside part of the objective lens. The eye - piece forms a real image of this line. The length of this image is I. The magnification of the telescope is 

A beam of light consisting of red, green and blue colours is incident on a right-angled prism. The refractive index of the material of the prism for the above red, green and blue wavelength are 1.39, 1.44 and 1.47

The Prism will

• separate the blue colour part from the red and green colours

• separate all the three colours from one another

• not separate the three colours at all

• separate the red colour part from the green and blue colours

On the first minimum adjacent to the central maximum of a single slit diffraction pattern, the phase  difference between the Huygens wavelet from the edge of the slit and the wavelet from the midpoint of the slit is

• π/4 radian

• π/2 radian

• π radian

• π radian