5.1 - 5.2 - Waves and Particle Nature of Light

Question 1

Define: amplitude, frequency, period, wavelength

Answer 1

Amplitude: maximum displacement from its equilibrium position
Frequency: number of complete waves that pass a point per second
Period: length of time taken for one complete wave to pass a given point
Wavelength: distance between the same point on two adjacent waves

Question 2

Describe a longitudinal wave

Answer 2

• particle oscillations are parallel to direction of waves motion
• consist of rarefactions (low pressure regions) and compressions (high pressure regions)

Question 3

Describe a transverse wave

Answer 3

• particle oscillations are perpendicular to direction of waves motion
• consist of peaks (max positive displacement) and troughs (max negative displacement)

Question 4

What is a progressive wave

Answer 4

• one that transfers energy from one point to another without transferring matter

Question 5

What is a standing wave

Answer 5

• a wave that stores energy rather than transferring it from one place to another

Question 6

What is path a measure of

Answer 6

• how far ahead one wave is to another

Question 7

What is a waves phase

Answer 7

• waves phase at a given point is a measure of how far through its cycle the wave is. Complete cycle is 360 degrees / 2pi rads

Question 8

What happens when two waves meet in phase

Answer 8

• they will interfere and undergo constructive interference

Question 9

What happens when two waves meet in antiphase

Answer 9

• they will interfere and undergo destructive interference

Question 10

How is a standing wave formed on a string

Answer 10

• a wave reflects from a closed end so two identical waves are travelling in opposite directions
• at points where the wave meets in phase constructive interference occurs forming anti node
• at points where the wave meets in anti phase destructive interference occurs forming a node

Question 11

What are nodes and anti-nodes

Answer 11

node - minimum point of displacement where there is no movement from equilibrium position
anti-node - a point of maximum displacement

Question 12

What two factors does the speed of a transverse wave on a string depend on

Answer 12

• time period
• mass per unit length of the string