Waves

Question 1

Progressive Wave

Answer 1

A wave that transfers energy without transferring material. Made up of particles of a medium oscillating.

Question 2

Amplitude

Answer 2

A wave’s maximum displacement from the equilibrium position.

Question 3

Frequency

Answer 3

The number of complete oscillations passing through a point per second.

Question 4

Wavelength

Answer 4

The length of one whole oscillation.

Question 5

Speed

Answer 5

Distance travelled by the wave per unit time.

Question 6

Phase

Answer 6

The position of a certain point on a wave cycle.

Question 7

Phase difference

Answer 7

How much a particle/wave lags behind another particle/wave.

Question 8

Period

Answer 8

Time taken for one full oscillation.

Question 9

What does it mean when two waves are in phase?

Answer 9

They are both at the same point of the wave cycle. They will have the same displacement and velocity. Phase difference will be a multiple of 360 degrees.

Question 10

What does it mean when two waves are out of phase?

Answer 10

When they’re an odd integer of half cycles apart.

Question 11

Transverse waves

Answer 11

Oscillation of particles at right angles to the direction of energy transfer.

Question 12

What kind of wave is a transverse wave?

Answer 12

All EM waves are trasverse and travel at 3x10^8 in a vacuum.

Question 13

Longitudinal waves

Answer 13

Oscillation of particles is parallel to the direction of energy transfer.

Question 14

Polarised

Answer 14

Wave that can only oscillate in only one plane.

Question 15

What kind of wave can be polarised?

Answer 15

Only transverse waves.

Question 16

Uses of polarisation

Answer 16

Sunglasses, reduce glare by blocking partially polarised light. TV and radio signals.

Question 17

Superposition

Answer 17

Where the displacements of two waves are combined as they pass each other. The resultant displacement is the vector sum of each wave’s displacement.

Question 18

Constructive interference

Answer 18

Occurs when two waves have displacement in the same direction.

Question 19

Destructive interference

Answer 19

Occurs when one wave has positive displacement and the other has negative displacement, if the wave has equal but opposite displacements, total destructive interference occurs.

Question 20

Stationary wave

Answer 20

Formed from the superposition of 2 progressive waves travelling in opposite directions with the same frequency, wavelength and amplitude.

Question 21

Antinodes

Answer 21

Are formed when waves meet in phase, constructive interference occurs. They are regions of maximum amplitude.

Question 22

Nodes

Answer 22

Waves are completely out of phase. Destructive interference occurs. Regions of no displacement.

Question 23

First harmonic

Answer 23

Forms a stationary wave with two nodes and a single antinode. The distance between adjacent nodes is half the wavelength.

Question 24

Stationary microwaves

Answer 24

Can be formed by reflecting a microwave beam at a metal plate, to find the nodes and antinodes use a microwave probe.

Question 25

Stationary sound waves

Answer 25

Can be formed by placing a speaker at one end of a closed glass tube, lay powder across the bottom of the tube, it will be shaken at the antinodes and settle at the nodes. The distance between each node is half a wavelength, and the frequency of the signal generator to the speaker is known so by c=fλ the speed of sound in air can be found.

Question 26

Path difference

Answer 26

The difference in the distance travelled by two waves.

Question 27

Coherent

Answer 27

A light source that has the same frequency and wavelength and a fixed phase difference.

Question 28

Monochromatic

Answer 28

Emit a single wavelength of light.

Question 29

Diffraction

Answer 29

The spreading out of waves when they pass through or around a gap.

Question 30

When does the greatest diffraction occur?

Answer 30

When the gap is the same size as the wavelength.

Question 31

When do you get less diffraction?

Answer 31

When the gap is smaller than the wavelength. Most of the wavelenght is reflected. When it is larger there is less notable diffraction.