SECTION-4 (Maximum Marks : 12)

• This section contains TWO (02) paragraphs.

• Based on each paragraph, there are TWO (02) questions.

• The answer to each question is a NUMERICAL VALUE.

• For each question, enter the correct numerical value of the answer using the mouse and the on-screen virtual numeric keypad in the place designated to enter the answer.

• If the numerical value has more than two decimal places, truncate/round-off the value to TWO decimal places.

• Answer to each question will be evaluated according to the following marking scheme:

Full Marks If ONLY the correct numerical value is entered in the designated place; .

Zero Marks : 0 In all other cases.

PARAGRAPH I

In a Young's double slit experiment, each of the two slits and , as shown in the figure, are oscillating about their fixed center and with a mean separation of . The distance between the slits at time is given by , where . The distance of the screen from the slits is and the wavelength of the light used to illuminate the slits is 6000 . The interference pattern on the screen changes with time, while the central bright fringe (zeroth fringe) remains fixed at point .

(i) The bright fringe above the point oscillates with time between two extreme positions. The separation between these two extreme positions, in micrometer ( ), is .

(ii) The maximum speed in at which the bright fringe will move is .