# 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 βcoherent lightβ?

• 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.
• ETwo or more light waves are coherent if they have the same frequency and amplitude.

Q2:

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

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

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?

• Aiv
• Biii
• Cv
• Dii
• Ei

Q5:

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

• Av
• Biii
• Civ
• Dii
• 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

Q7:

The following five functions can be used to model five light waves. Which of the five waves is not coherent with the other four?

• A
• B
• C
• D
• E

Q8:

The following five functions can be used to model five light waves.

Which of the five waves is not coherent with the other four?

• Aiv
• Bi
• Cii
• Dv
• Eiii

Q9:

The following five functions can be used to model five light waves:

Which of the five waves is not coherent with the other four?

• Aiii
• Biv
• Ci
• Dii
• Ev

Q10:

The following two functions can be used to model two light waves:

What value for would make these two waves coherent?

Q11:

The following two functions can be used to model two light waves:

What value for would make these two waves coherent?

• A
• B
• C
• D
• E