Chap 12: Superposition

Question 1

● Principle of Superposition:

Answer 1

When two or more waves meet at a point, the resultant displacement at that point is equal to the vector sum of the displacements due to the individual waves at that point

Question 2

● Interference:

Answer 2

Effect that occurs when two or more waves overlap; the resultant displacement at each point in the overlapping region is the vector sum of the displacements of the overlapping waves.

Question 3

● Phase difference (between two waves):

Answer 3

Measure of the fraction of a cycle that one wave is moving out of step with the other wave.

Question 4

● Coherence:

Answer 4

Constant phase difference between the waves (or sources of waves) with time.

Question 5

● Path difference:

Answer 5

Difference in distances that one wave travels compared with another wave from the sources to reach a particular point.

Question 6

● Conditions for observable interference

Answer 6

○ The sources or waves are coherent.
○ Waves from sources have similar amplitudes.
○ Waves from the sources must overlap.
○ Waves are of the same type.
○ For polarised transverse waves, waves must have the same plane of polarisation.

Question 7

● Diffraction:

Answer 7

Spreading of waves after passing through a slit or around the edge of an obstacle.

Question 8

When does the limit of resolution or resolving power of an aperture occur?

Answer 8

Limit of resolution or resolving power of an aperture occurs when the central maximum of the second source coincides with the first minimum of the first source.

Question 9

Rayleigh criterion

Answer 9

The images of two point sources are considered just resolved if the central maximum of the images coincides with the first minimum of the other source