Wave Optics Tes...

What is not an essential condition for an observable interference pattern to occur between the waves two sources?

In a double slit experiment, when a thin film of thickness $$t$$ having refractive index $$\mu$$ is introduced in front of one of the slits, the maximum at the centre of the fringe pattern shifts by one fringe width. The value of $$t$$ is ($$\lambda$$ is the wavelength of the light used) : 

A plane wavefront of wavelength $$\lambda$$ is incident on a single slit of width a. The angular width of principal maximum is?

What is the amplitude of resultant wave, when two waves $$y_1=A_1\sin (\omega t-B_1)$$ and $$y_2=A_2\sin (\omega t-B_2)$$ superimpose ?

If at the focus of a convex lens of focal length $$6$$ metre,a point source of $$36$$ condela is placed, then the illuminance on a screen placed normally to teh emergent beam of light is:

A ray of light is coming from the source $$S$$. If a thin film of thickness $$t$$ and refractive index $$\mu$$ is placed in its path, the increase in length of optical path is :

To obtain a good photographic print, an exposure of $$2s$$ at a distance of $$1\ m$$ from a $$75\ cd$$ bulb is done. To obtain an equally satisfactory result, what should be the distance, if time of exposure is $$12\ s$$ from a $$50\ cd$$ bulb?

Which of these waves can be polarised ?

If the width of slit is gradually increased, it will be observed experimentally that :

An astronaut is approaching the moon. He sends out a radio signal of frequency $$5000\ MHz$$ and the frequency of echo is different from that of the original frequency by $$100\ kHz$$. His velocity of approach with respect to the moon is: