Wave Motion and Superposition

Question 1

What is coherence?

Answer 1

Waves or sources with constant phase difference

Question 2

Explain how the stationary is formed on a stretched string?

Answer 2

Waves are reflected at the pulley end (where it is attached to). This produces nodes and antinodes on the string.

Question 3

State the principle of superposition of waves

Answer 3

(When two or more waves meet at a point in space) the resultant (displacement) is equal to the (vector) sum of the individual displacements of waves (meeting at a point)

Question 4

What is amplitude?

Answer 4

The maximum distance moved from the rest point.

Question 5

What is displacement?

Answer 5

The distance moved, in a particular direction, from the rest point by an oscillating particle.

Question 6

What is wavelength?

Answer 6

The length for one complete cycle.

Question 7

What is period?

Answer 7

The time taken for one complete cycle.

Question 8

What is frequency?

Answer 8

The number of cycles per unit time.

Question 9

What is intensity?

Answer 9

The power per unit cross-sectional area.

Question 10

What is a longitudinal wave?

Answer 10

A wave where the oscillations of the particles or field are parallel to the direction of motion of the wave.

Question 11

What is a transverse wave?

Answer 11

A wave where the oscillations of the particles or field are perpendicular to the direction of motion of the wave.

Question 12

What is a progressive wave?

Answer 12

A wave which transfers energy or information through the medium as a result of the oscillations of particles
or a field.

Question 13

What is a standing wave?

Answer 13

A wave which does not transfer energy or information through the medium as a result of the oscillations of
particles or a field.

Question 14

What is phase difference?

Answer 14

The amount by which two waves are out of step with each other.

Question 15

What is path difference?

Answer 15

The difference in distance travelled for two waves coming from different sources but reaching the same point.

Question 16

What is wave speed?

Answer 16

The distance travelled by a wave per unit time. Given by the product of the wavelength and frequency of a
wave.

Question 17

What is interference?

Answer 17

When two or more coherent waves of the same type overlap and their displacements sum together, changing the
overall intensity.

Question 18

What is constructive interference?

Answer 18

Waves have a phase difference of 0° so that the interference produces a maximum possible displacement.

Question 19

What is destructive interference?

Answer 19

Waves have a phase difference of 180° so that the interference produces a minimum possible displacement.

Question 20

What is a node?

Answer 20

The point on a standing wave, created by destructive interference such that there is no movement.

Question 21

What is an antinode?

Answer 21

The point on a standing wave, created by constructive interference such that there is maximum movement.

Question 22

What is the fundamental mode of vibration?

Answer 22

The standing wave of largest wavelength that can exist.

Question 23

What is the fundamental wavelength?

Answer 23

The highest wavelength of standing wave that can exist in a system.

Question 24

What is the fundamental frequency?

Answer 24

The lowest frequency of standing wave that can exist in a system.

Question 25

What is a harmonic?

Answer 25

A standing wave which has a frequency which is a multiple of the fundamental frequency.

Question 26

What is the refractive index?

Answer 26

(Speed of light in a vacuum)/(Speed of light in that material)

Question 27

What is a plane polarised wave?

Answer 27

A transverse wave whose oscillations in one direction are confined to a single plane.