For sustained interference we need two sources which emit waves:
To obtain well-defined interference patterns, the intensity at points corresponding to destructive interference must be zero, while intensity at the point corresponding to constructive interference must be maximum. To accomplish this the necessary condition is that the two interference sources must be coherent, that is, they must keep a constant phase difference.
When the interference occurs with coherent sources, _______ of the superimposingwaves add like _______.
Two sources of light are said to be coherent when both give out light waves of same:
In physics, two wave sources are perfectly coherent if they have a constant phase difference and the same frequency (amplitude may be different).
As c be the speed of light which is constant.
Now same ν gives same λ. for the two light sources.
Example: y1=A1sinwt and y2=A2sin(wt+ϕ) where ϕ is constant.
Phase difference between two coherent sources should be:
Coherent sources can be created by the division of:
In a Fresnel’s biprism experiment, the two coherent sources are obtained by:
A 60.0 kHz transmitter sends an EM wave to a receiver 21 km away. The signal also travels to the receiver by another path where it reflects from a helicopter. Assume that there is a 180o phase shift when the wave is reflected. This situation will give ________.
Correct Answer : b
Explanation : When an incident light ray reflects from a boundary with a higher index of refraction, the reflected wave is inverted (a 180° phase shift is introduced).
f = 60kHz
f = 60,000Hz
v = 3 * 108m/s
v = f * λ
(3*108) = 60000
λ = 5km
The path length difference is λ = 5 km = , a whole number of wavelengths. Since there is also a 180 phase shift there will be destructive interference
Light of wavelength λ in vacuum enters a medium of refractive index μ. Two points in this medium, lying along the path of this light, are at a distance x apart. The phase difference between these points is
λ is the wavelength of light in air.
Let t be the distance between points S and A.
Optical path length travelled by light via SB
Optical path length travelled by light via SA = μt
Path difference between points A and B
Now phase difference
Which of the following is not essential for two sources of light in Young’s double slit experiment to produce a sustained interference?
Which of the following is not an example of coherent source produced by the division of wavefront?