Wave Optics Tes...

The waves are observed by a child sitting in a rowboat off shore. Which of the following properties of the waves seen by the child would be greater when the boat is moving away from the beach than the boat is stationary with respect to the beach?
I. Speed of the waves with respect to the boat.
II. Frequency at which the boat encounters successive wave crests.
III. Distance between adjacent wave crests

In which of the following cases do we obtain a plane wave front?

How does the fringe width in a double slit interference pattern change, when the distance between the slits is increased ?

In a double slit experiment $$ D=1m,d=0 .2cm$$ and$$\lambda={ 6000 }\mathring { A }$$. The distance of the point from the central maximum where intensity is $$75\%$$ of the at the centre will be:

In Young's double slit experiment, $$5^{th}$$ dark fringe is formed opposite to one of the slits. If $$D$$ is the distance between slits and the screen, and $$d$$ is the separation between the slits, then the wavelength of light used is ?

Which of the following is incorrect?

The two coherent sources of equal intensity produce maximum intensity of $$100$$ units at a point. If the intensity of one of the sources is reduced by $$50\%$$ by reducing its width then the intensity of light at the same point will be

The speed of the light in the medium is :- 

Two superimposing waves are represented by equation $${y}_{1}=2\sin { 2\pi  } \left( 10t-0.4x \right)$$ and $${y}_{2}=4\sin { 2\pi  } \left( 20t-0.8x \right)$$. The ratio of $${I}_{max}$$ to $${I}_{min}$$ is