question_answer

Directions for: The questions consist of two statements each, printed as assertion and reason. While answering these questions you are required to choose any one of the following five responses A. If both the Assertion and the Reason are true and the Reason is a correct explanation of the Assertion. B. If both the Assertion and the Reason are true but the Reason is not a correct explanation of Assertion. C. If the Assertion is true but the Reason is false. D. If both the Assertion and the Reason are false. E. If Assertion is false but Reason is true.

Assertion: In Youngs experiment, the fringe width tor dark fringes is different from that for white fringes. Reason: In Youngs double slit experiment when the fringes are performed with a source of white light, then only black and bright fringe are observed.

A)  A            

B)                         B           

C)                         C                           

D)         D

E)  E

Correct Answer: D

Solution :

                             Thomas Young demonstrated experimentally the phenomenon of interference of light. For \[{{S}_{1}}\] and \[{{S}_{2}}\] being two coherent sources and distance between source and screen is D, then interference pattern consists of dark and white fringes. Fringe width for both is same. \[W=\frac{D\lambda }{d}\], where \[\lambda \] is wavelength. Also for white light source colored fringes are formed.