12.1+12.2 Superposition, Interference

Question 1

what is the principle of superposition?

Answer 1

when two or more waves meet at one point, the resultant displacemnet is the vector sum of the individual displacement

Question 2

what is constructive interference?

Answer 2

• waves meet in phase
• maximum positive displacement of each sum

Question 3

what is destructive interference?

Answer 3

• waves meet in anti phase
• maximum positive displacement of one waves sums the maximum negative displacement of the other wave
• the waves cancel out

after destructive interferncence can have a non zero amplitude

Question 4

what is inerference?

Answer 4

the effect/ pattern observed upon the superposition of two coherent waves

waves must be coherant to interfere

Question 5

what is the required condition for interference effects to be observed?

Answer 5

when two coherent waves superpose

Question 6

what are coherent waves?

Answer 6

maintain a constant phase difference at a given point, throughout time
* two waves must have the same frequency

Question 7

what is path difference?

Answer 7

difference in distance travelled by the two waves

Question 8

how does path difference link to phase difference?

Answer 8

Question 9

Answer 9

Question 10

what is the formula betwen phase difference and path difference?

Answer 10

Question 11

what are the conditions needed for constructive interference (consecutive maxima) ?

Answer 11

• path length difference to be an interger multiple of wavelength
• phase difference to be a multiple of 2 π (360)

Question 12

what are the conditions needs for destructive interference (constructive minima)?

Answer 12

• an odd multiple of half wavelength( λ/2) eg: 3.5 λ
• a phase difference of an odd multiple of π (3π- 270)

Question 13

Draw the maxima and minima caused by path and phase difference

Answer 13

Question 14

Answer 14