Coherent and Incoherent Addition of Waves

Two sources are called coherent if they produce waves ______________ .

Two source S₁ and S₂ of intensity I₁ and I₂ are placed in front of a screen [Figure (a)]. The pattern of intensity distribution seen in the central portion is given by Figure (b).

(a)

(b)

1. S₁ and S₂ have the same intensities.
2. S₁ and S₂ have a constant phase difference.
3. S₁ and S₂ have the same phase.
4. S₁ and S₂ have the same wavelength.

Two coherent sources of different intensities send waves which interfere. The ratio of maximum intensity to the minimum intensity is 25. The intensities of the sources are in the ratio ______.

When a tiny circular obstacle is placed in the path of light from a distant source, a bright spot is seen at the centre of the shadow of the obstacle. Explain why?

Two coherent point sources S₁ and S_2, vibrating in phase, emit light of wavelength \[\lambda.\] The separation between the sources is \[2\lambda.\] Consider a line passing through S₂ and perpendicular to the line S₁ S₂. What is the smallest distance from S₂ where a minimum intensity occurs?

Two sources of light are coherent if they have ______.

n identical waves each of intensity I₀ interfere with each other. The ratio of maximum intensities if the interference is (i) coherent and (ii) incoherent is ______.