The phase difference between the two reflected ways counts, and it is not zero, even in the case when the path difference --->0.sheld said:Why the center of Newton's ring is dark? though I am thinking the path difference in the center is zero between two reflected rays...
so,I will be glad if u give the correct information about that...
The dark spot in the center of Newton's Rings is caused by destructive interference of light waves. When light is reflected off the curved surface of a lens or a curved glass plate, it creates concentric rings of light due to the phenomenon of interference. However, at the exact center point, the path difference between the reflected waves is zero, resulting in destructive interference and a dark spot.
The path difference theory explains the dark center of Newton's Rings by considering the difference in the path lengths of the light waves that are reflected off the curved surface. When the path difference is equal to half of the wavelength of light, the waves will be out of phase and cancel each other out, resulting in a dark spot at the center.
The rings get smaller as they move away from the dark center because the path difference between the reflected waves increases, causing the waves to become more out of phase and resulting in more destructive interference. This leads to a decrease in the intensity of light and the appearance of smaller rings.
Yes, the path difference theory can be applied to other interference patterns such as Young's double slit experiment and thin film interference. In these cases, the path difference between the two waves determines the interference pattern observed, whether it is constructive or destructive interference.
The path difference in Newton's Rings can be calculated by using the formula Δx = 2nt, where Δx is the path difference, n is the refractive index of the medium between the lens and the glass plate, and t is the thickness of the air wedge formed between them. This formula can be used to determine the number of dark and bright fringes observed in the interference pattern.