YDSE Fringe Width and White Light – Rankers Physics

Young's Double Slit Experiment: Practice Problem & Solution

Assertion (A): In Young's experiment, the fringe width for dark fringes is different from that for bright fringes. Reason (R): In Young's double slit experiment with a source of white light, only black and white fringes are observed.  
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Young's Double Slit Experiment. Understanding the underlying formula is key to arriving at the correct answer below:

In YDSE, the fringe width is given by \(\beta = \frac{\lambda D}{d}\), which is independent of whether the fringe is bright or dark. Hence, A is false. With white light, a central bright white fringe is formed, and then colored fringes are observed, not just black and white. Hence, R is false.

Leave a Reply

Your email address will not be published. Required fields are marked *

Similar Practice Questions

Explore conceptually related problems to test your knowledge.

1. In the Young’s double slit experiment using a monochromatic light of wavelength λ , the path difference ( in terms of an integer n) corresponding to any point having half the peak intensity is
2. The interference pattern is obtained with two coherent light sources of intensity ratio n. In the interference pattern, the ratio $\frac{I_{max} - I_{min}}{I_{max} + I_{min}}$ will be: (2016 - II)
3. Assertion (A): The stars which are not resolved in the image produced by the objective of a telescope can't be further resolved by its eye piece. Reason (R): The primary purpose of eyepiece of telescope is to provide the magnification of image produced by the objective.  
4. Assertion (A): When a monochromatic light beam is incident normally on a reflective surface, under some condition it is possible that all lights is transmitted without any reflection. Reason (R): When light after passing through a polaroid is incident on a reflecting surface at angle of incidence equals to polarizing angle, then all light gets transmitted without any reflection.
5. In Young's double slit experiment, the fringe width is found to be 0.4 mm. If the whole apparatus is immersed in water of refractive index 4/3 without disturbing the geometrical arrangement, the new fringe width will be: (1990)