YDSE Phase Difference and Bright Fringe – Rankers Physics

Young's Double Slit Experiment: Practice Problem & Solution

Assertion (A): In standard YDSE set up with visible light, the position on screen where phase difference is zero appears bright. Reason (R): In YDSE set up amplitude of electromagnetic field at central bright fringe is not varying with time.  
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

Solution Explained:

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:

A zero phase difference signifies constructive interference, resulting in a bright fringe. Hence, A is true. The amplitude of the electromagnetic field at the central bright fringe remains constant over time in a stable interference pattern, but this is not the reason for it being bright due to zero phase difference. Hence, R is true but not the correct explanation for A.

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Similar Practice Questions

Explore conceptually related problems to test your knowledge.

1. Assertion (A): In Young's double slit experiment, if one of the slits is closed, intensity at the position of central fringe becomes half. Reason (R): Resultant intensity, being sum of intensities from individual slits, becomes half as one slit is closed.  
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. In Young's experiment, two coherent sources are placed 0.90 mm apart and fringe are observed one metre away. If it produces second dark fringe at a distance of 1 mm from central fringe, the wavelength of monochromatic light is used would be: (1991)
4. In a diffraction pattern due to a single slit of width a, the first minima is observed at an angle $30^\circ$ when light of wavelength $5000 \AA$ is incident on the slit. The first secondary maximum is observed at an angle of: (2016 - I)
5. In YDSE setup, light of wavelength 640 nm is used with d = 0.8 m m and D = 1m . If intensity at central maxima is I0 and it's position is y = 0,