Interference Pattern Contrast – Rankers Physics

Young's Double Slit Experiment: Practice Problem & Solution

Assertion (A): The best contrast of the interference pattern is obtained when the intensity of the emerging lights from the two slits of the Young's experimental set-up are equal. Reason (R): Intensity is proportional to the square of the amplitude.  
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:

For best contrast in an interference pattern, the amplitudes of the interfering waves must be equal, implying equal intensities. Intensity \(I\) is proportional to the square of the amplitude \(A\), i.e., \(I \propto A^2\). Thus, equal intensities lead to maximum contrast.

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Your email address will not be published.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 a Young's double slit experiment, a student observes 8 fringes in a certain segment of screen when a monochromatic light of 600 nm wavelength is used. If the wavelength of light is changed to 400 nm, then the number of fringes he would observe in the same region of the screen is (2022)
2. Two coherent sources of light can be obtained by :
3. Assertion (A): On increasing wavelength of light used, resolving power increases. Reason (R): On increasing wavelength, width of central maxima decreases.  
4. In Young's double slit experiment, the slits are 2 mm apart and are illuminated by photons of two wavelengths $\lambda_1 = 12000 \AA$ and $\lambda_2 = 10000 \AA$. At what minimum distance from the common central bright fringe on the screen 2 m from the slit will a bright fringe from one interference pattern coincide with a bright fringe from the other? (2013)
5. An astronomical refracting telescope will have large angular magnification and high angular resolution, when it has an objective lens of (2018)