When interference happens with two monochromatic light waves, which of the following is a characteristic of the amplitude of the resultant wave?
a. it is zero.
b. it is equal to the sum of the amplitudes of the component waves.
c. less than the amplitude of either of the component waves.
d. greater than the amplitude of either of the component waves.
http://en.wikipedia.org/wiki/Interference_(wave_propagation)
note:
[2A] cos (kx- wt) cos(phase angle/2)
"The principle of superposition of waves states that when two or more propagating waves of same type are incident on the same point, the resultant amplitude at that point is equal to the vector sum of the amplitudes of the individual waves."
Is the answer b?
yes
When interference occurs between two monochromatic light waves, the resultant wave is the combined effect of the two waves. The characteristic of the amplitude of the resultant wave depends on the phase difference between the two waves.
If the two waves are in phase, meaning their crests and troughs align perfectly, they will constructively interfere. In this case, the amplitude of the resultant wave will be greater than the amplitude of either of the component waves. This corresponds to option (d).
If the two waves are completely out of phase, meaning their crests and troughs are completely opposite, they will destructively interfere. In this case, the amplitude of the resultant wave will be zero. This corresponds to option (a).
If the two waves have a phase difference between 0 and 180 degrees, they will partially interfere. In this case, the amplitude of the resultant wave will be less than the amplitude of either of the component waves. This corresponds to option (c).
So, in summary, depending on the phase difference, the resultant wave's amplitude can be zero (a), greater than the amplitude of either component wave (d), or less than the amplitude of either component wave (c).