Assertion: In Young's double slit experiment, | vedclass

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(D) In Young's double slit experiment,the fringe width is given by $\beta = \frac{\lambda D}{d}$.The number of bright fringes $N$ that can be observed

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If both the Assertion and Reason are incorrect.

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(D) In Young's double slit experiment,the fringe width is given by $\beta = \frac{\lambda D}{d}$.The number of bright fringes $N$ that can be observed on a screen of width $W$ is given by $N = \frac{W}{\beta} = \frac{Wd}{\lambda D}$.From this relation,it is clear that the number of fringes $N$ is inversely proportional to the wavelength $\lambda$ $(N \propto \frac{1}{\lambda})$.If the wavelength $\lambda$ is doubled,the number of fringes $N$ will be halved,meaning it decreases.Therefore,the Assertion is incorrect because the number of fringes decreases,not increases.The Reason is also incorrect because the number of fringes is inversely proportional to the wavelength,not directly proportional.Thus,both the Assertion and the Reason are incorrect.

Assertion: In Young's double slit experiment,if the wavelength of incident monochromatic light is doubled,the number of bright fringes on the screen will increase.
Reason: The maximum number of bright fringes on the screen is directly proportional to the wavelength of light used.

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Assertion: In Young's double slit experiment,if the wavelength of incident monochromatic light is doubled,the number of bright fringes on the screen will increase.Reason: The maximum number of bright fringes on the screen is directly proportional to the wavelength of light used.