INTERFERENCE Flashcards
(17 cards)
What are the two types of interference?
Interference can be constructive or destructive.
What conditions must be met for interference to occur?
The two waves must be coherent — having the same wavelength and frequency, and a fixed phase difference.
What is the path difference for constructive interference?
Path difference = nλ.
What is the path difference for destructive interference?
Path difference = (n + 1/2)λ.
What did Young’s double slit experiment demonstrate?
It showed the wave nature of light.
What happens when light passes through two closely spaced slits?
Alternate bright and dark fringes, known as ‘Young’s fringes’, are seen on a screen.
What is the formula for fringe separation, w?
w = λD/s.
How should fringe separation be measured?
Measure across several dark fringes and divide by the number of fringes measured.
What is the appearance of fringes when using white light?
The central fringe is white, inner fringes are tinged with blue on the inside and red on the outside, and outer fringes merge into an indistinct background of white light.
What is diffraction?
Diffraction occurs when waves pass through a gap similar in width to the wavelength.
What is the relationship between slit width and fringe width?
Width of central fringe ∝ λ.
What is the formula for diffraction gratings?
d sin θ = nλ.
What is the significance of X-ray diffraction?
X-ray λ is similar to atom spacing in a crystalline structure, allowing for diffraction patterns to be formed.
What are the types of spectra?
Continuous, line emission, and line absorption.
What does the absolute refractive index measure?
It measures optical density.
What is the critical angle in total internal reflection?
If light is incident at θc to the normal, it will exit along the flat surface.
What issues are encountered with fiber optics?
Absorption, modal dispersion, and material dispersion.
