Waves 67-77 82-87

Question 1

What’s a progressive wave?

Answer 1

A ​progressive wave transfers energy without transferring material​ ​and is made up of particles of a medium oscillating​

Question 2

Define amplitude

Answer 2

A wave’s maximum displacement from the equilibrium position ​(units are m)

Question 3

Define frequency

Answer 3

The number of complete oscillations passing through a point per second, (units are Hz)

Question 4

Define wavelength

Answer 4

The length of one whole oscillation

Question 5

Define speed

Answer 5

Distance travelled by the wave per unit time, ​(units are m/s)

Question 6

Define phase

Answer 6

The position of a certain point on a wave cycle, ​(units are radians, degrees or fractions of a cycle)

Question 7

Define phase difference

Answer 7

How much a particle/wave lags behind another particle/wave, ​(units are radians, degrees or fractions of a cycle)

Question 8

Define a period

Answer 8

Time taken for one full oscillation, ​(units are s)

Question 9

What’s does it mean when 2 points on a wave are in phase?

Answer 9

If they are both at the same point of the wave cycle, they will have the ​same displacement and velocity ​and their​ phase difference will be a multiple of 360° (2π radians), they do not need the same amplitude, only the same frequency and wavelength.

Question 10

What’s does it mean when 2 points on a wave are not in phase?

Answer 10

When they’re an​ ​odd integer of half cycles apart​ e.g. 5 half cycles apart where one half cycle is 180° (π radians).

Question 11

How do you calculate the speed of a wave?

Answer 11

C = fλ

Question 12

How do you calculate the frequency of a wave?

Answer 12

F = 1 / T

Question 13

What’s a transverse wave and give 2 examples?

Answer 13

Oscillation of particles is at​ right angles to the direction of energy transfer
Electromagnetic waves and water waves

Question 14

What’s a longitudinal wave and give 2 examples?

Answer 14

Oscillation of particles is ​parallel to the direction of energy transfer and are made up of compressions and rarefractions
Sound waves and ultrasound waves

Question 15

Which type of wave can travel in a vacuum?

Answer 15

Transverse

Question 16

What’s is polarisation?

Answer 16

Restricting the vibrations of a transverse wave, especially light, wholly or partially to one direction

Question 17

When can polarisation occur?

Answer 17

If a wave’s oscillations are perpendicular to its direction of travel (as they are in transverse waves)

Question 18

What is superstition?

Answer 18

Where the ​displacements​ of two waves are combined as they pass each other

Question 19

What are the 2 types of interference that can occur during superstition?

Answer 19

Constructive interference​ occurs when 2 waves have displacement in the ​same direction
Destructive interference​ occurs when one wave has positive displacement and the other has negative displacement, if the waves have equal but ​opposite​ displacements

Question 20

How is a stationary wave formed?

Answer 20

The superposition of 2 progressive waves​, travelling in opposite directions ​in the same plane, with the ​same​ ​frequency, wavelength and amplitude

Question 21

What happens when the waves meet in phase?

Answer 21

Constructive interference​ occurs so ​antinodes​ are formed, which are regions of maximum amplitude

Question 22

What happens when the waves meet completely out of phase?

Answer 22

Destructive interference​ occurs and nodes​ are formed, which are regions of no displacement

Question 23

What is the first harmonic?

Answer 23

The lowest frequency that a stationary wave forms is called the first harmonic (2 nodes 1 anti node)

Question 24

What is the distance between adjacent nodes / anti nodes in any harmonic?

Answer 24

Half the wavelength