12 - Waves 2

Question 1

principle of superposition

Answer 1

when two similar types of waves meet at a point the resultant displacement at that point is equal to the sum of the displacements of the individual waves

Question 2

superposition

Answer 2

overlap of two waves at a point in space

Question 3

interference

Answer 3

superposition of two progressive waves from coherent sources to produce a resultant wave with a displacement equal to the sum of the individual displacements from the two waves

Question 4

constructive interference

Answer 4

superposition of two waves in phase so that the resultant wave has a greater amplitude than the original waves

Question 5

destructive interference

Answer 5

superposition of two waves in antiphase so that the waves cancel each other out and the resultant wave has smaller amplitude than the original waves

Question 6

interference pattern

Answer 6

a pattern of constructive and destructive interference formed as waves overlap

Question 7

coherence

Answer 7

two wave sources, or waves, that are coherent have a constant phase difference

Question 8

path difference

Answer 8

the difference in the distance travelled by two waves from their source to a specific point

Question 9

maximum (maxima)

Answer 9

point of greatest amplitude in an interference patters

Question 10

minimum (minima)

Answer 10

point of least amplitude in an interference patters, produced by destructive interference

Question 11

monochromatic light

Answer 11

light of a single frequency

Question 12

stationary (or standing) wave

Answer 12

a wave that remains in a constant position with no net transfer of energy and is characterised by its nodes and antinodes

Question 13

node

Answer 13

for a stationary wave, a point where the displacement is always zero, therefore the amplitude and intensity are zero

Question 14

antinode

Answer 14

for a stationary wave, the point of greatest amplitude

Question 15

describe Young’s double split experiment and state what classical theory it successfully demonstrated (6)

Answer 15

• Young used a source of monochromatic light (1) and passed it through a single slit (1), the light diffracting from this is in phase. This wave then passed through double slit (1) and diffracting waves interfere (1) and cause areas of maxima and minima known as fringes (1)
• confirmed classical wave nature of light (1)

Question 16

fundamental node of vibration

Answer 16

a vibration at the fundamental frequency

Question 17

fundamental frequency

Answer 17

the lowest frequency at which an object can vibrate

Question 18

harmonic

Answer 18

a whole-number multiple of the fundamental frequency