Question

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

• A. can be obtained by 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

Answer: (B)

can be obtained by using sources $3$ and $4$

Different wavelengths would correspond to different frequencies whereas lights of different frequencies give different coherence even if contrast is poor.

Hence we can say that coherence obtains by using light of different intensities .