Waves

Question 1

How do you calculated the period and velocity of a wave?

Answer 1

P = 1/f
v = fλ = λ/t

Question 2

What is the difference between a transverse and longitudinal wave?

Answer 2

transverse - the oscillations are perpendicular to the transfer of energy
longitudinal - the oscillations are parallel to the transfer of energy

Question 3

What happens when a wave reaches a boundary between two materials?

Answer 3

It will always be partially reflected, transmitted and absorbed

Question 4

What is the difference between angle of incidence and angle of reflection?

Answer 4

angle of incidence is the angle between the incident ray and the imaginary normal. angle of reflection is the angle between the refracted ray and the imaginary normal.

Question 5

Define diffraction.

Answer 5

When a plane wave passes through a narrow opening or obstacle, it bends around the object

Question 6

Define superposition

Answer 6

When two or more waves overlap in one space

Question 7

What is the difference between a node and an antinode?

Answer 7

Antinodes are points on a standing wave with maximum amplitude. Nodes are points of zero amplitude and appear to be fixed.

Question 8

What is the difference between constructive and destructive interference?

Answer 8

constructive is when two waves on the same side of the equilibrium overlap and superpose to make a bigger one
destructive when two waves on the opposite side of the equilibrium overlap and superpose to make a smaller one

Question 9

What effects the speed of sound?

Answer 9

The medium it is travelling through and its temperature

Question 10

Define elastic modulus

Answer 10

The stiffness of the structure of a material that effects the speed of sound travelling through it

Question 11

What is the fundamental frequency?

Answer 11

It is the first harmonic which is the smallest and the lowest of the frequencies. It is 1/2 a wavelength.

Question 12

What is the properties of a standing wave?

Answer 12

• formed from superposition (two waves of the same amplitude and frequency travel at each other)
• produces resonant frequencies
• are a result of resonance
• fundamental frequency usually has the greatest amplitude which decrease each harmonic

Question 13

What does a length of a pipe effect?

Answer 13

the frequency of the sounds that will resonate from it

Question 14

How does the opening of a pipe effect the nodes and anitnodes?

Answer 14

an open end will have a anit-node

a closed end will have a node

Question 15

Define resonance

Answer 15

when an object is exposed to vibrations at a frequency equal to its resonant frequency which is a specific frequency for that particular object

Question 16

What two effects occur when the natural frequency of an object is matched by its forcing frequency?

Answer 16

1. The amplitude of the oscillations will increase dramatically
2. The max. possible energy from the source will be transferred to the resonating object
   This is why things smash eg. glass

Question 17

Define Huygens’ Principle

Answer 17

The each point on a wavefront can be considered as a source of secondary wavelets