Question

Sources 1 and 2 emit lights of different wavelengths whereas sources 3 and 4 emit lights of different intensities. The coherence

• A. can be obtained by using sources 1 and 2
• B. can be obtained by using sources 3 and 4
• C. cannot be obtained by any of these sources
• D. since contrast suffers when sources 3 and 4 are used so coherence cannot be obtained by using sources 3 and 4

Answer 1

The correct option is B can be obtained by using sources 3 and 4

the coherence can be obtained by using sources 3 and 4 as only the intensities are different so their frequencies can be equal
for a coherent sources frequencies must be equal
option $B$ is correct