# Worksheet: Coherent Light

In this worksheet, we will practice determining whether two or more electromagnetic waves will interfere to form coherent or incoherent light.

Q1:

Which of the following statements correctly defines what is meant by the term “coherent light”?

• ATwo or more light waves are coherent if they have the same frequency and a constant phase difference.
• BTwo or more light waves are coherent if they have the same amplitude and a constant phase difference.
• CTwo or more light waves are coherent if they have a constant phase difference.
• DTwo or more light waves are coherent if they have the same frequency and amplitude.
• ETwo or more light waves are coherent if they have the same frequency.

Q2:

Which of the following statements correctly defines what is meant by incoherent light?

• ATwo or more light waves are incoherent if they have different frequencies or nonconstant phase differences.
• BTwo or more light waves are incoherent if they have different amplitudes.
• CTwo or more light waves are incoherent if they have both different amplitudes and nonconstant phase differences.
• DTwo or more light waves are incoherent if they have both different frequencies and different amplitudes.
• ETwo or more light waves are incoherent if they have the same frequency and constant phase differences.

Q3:

In each of the following diagrams, five light waves are shown. Which of the diagrams shows coherent light?

• A
• B
• C
• D
• E

Q4:

The figure shows five light waves. Which light wave is not coherent with the other four?

• Aiii
• Biv
• Ci
• Dv
• Eii

Q5:

The figure shows five light waves. Which light wave is not coherent with the other four?

• Aiv
• Bv
• Cii
• Diii
• Ei

Q6:

In each of the following diagrams, five light waves are shown. Which of the diagrams shows incoherent light?

• A
• B
• C
• D
• E