Electrons, Waves and Photons

Question 1

What is Wavelength

Answer 1

The smallest distance between two points that have the same pattern of oscillation

Question 2

What is the Time Period

Answer 2

The time taken for one complete pattern of oscillation to take place at any point

Question 3

What is Frequency

Answer 3

The number of oscillations per unit time

Question 4

What is displacement?

Answer 4

The distance any part of the wave has moved from its rest position

Question 5

What is Amplitude?

Answer 5

The maximum displacement

Question 6

What is a Progressive Wave

Answer 6

A wave that transfers energy as a result of oscillations of the medium through which energy is travelling without the transfer of the medium

Question 7

What is a Transverse Wave

Answer 7

Waves where the oscillations of the particles are perpendicular to the direction of wave propagation

Question 8

What is a Longitudinal Wave?

Answer 8

Waves where the oscillations of the particles are parallel to the direction of wave propagation

Question 9

Derive the wave equation?

Answer 9

V = S/t-> v = distance travelled in one cycle. . time taken for one cycle —> v = lamda/ time

Question 10

What are Cathode Ray Oscilloscopes

Answer 10

They allow the visualisation of transverse and longitudinal waves on a screen

Question 11

Equation for Intensity

Answer 11

Intensity = Power/ Area

Question 12

What is an Electromagnetic Wave?

Answer 12

An electromagnetic wave is a transverse wave consisting of oscillating electric and magnetic fields at right angles to each other

Question 13

What is Unpolarised Wave?

Answer 13

Light waves in which the electric and magnetic fields vibrate in all directions perpendicular to the direction of travel of the wave

Question 14

What is Plane Polarised Light?

Answer 14

Light waves in which the electric and magnetic fields vibrate in one direction (on a single plane) perpendicular to the direction of travel of the wave

Question 15

What is the Plane of Polarisation of an electromagnetic wave?

Answer 15

The plane in which the electric field oscillates

Question 16

What is Polarisation

Answer 16

The process of turning unpolarised light into polarised light

Question 17

What is the Rule of Reflection?

Answer 17

Angle of incidence is always equal to the angle of reflection

Question 18

Uses of concave surfaces

Answer 18

Satellite dishes

Question 19

Uses of convex surfaces

Answer 19

Wing mirrors

Question 20

What is Diffraction

Answer 20

The process of a wave spreading out after it has passed around an obstacle or through a skirt

Question 21

When does a wave experience maximum diffraction

Answer 21

A high frequency (short wavelength) wave doesn’t diffract as much as a low frequent (long wavelength) wave does A wave experiences maximum diffraction when the gap is equal to its wavelength

Question 22

What is intensity

Answer 22

Intensity is the energy per square metre per second or Power per square metre

Question 23

What is Superposition

Answer 23

Two waves combined at the same poiny

Question 24

What is the Constructive Inteference

Answer 24

When two waves are combined together to be completely in phase

Question 25

When will a Wave constructively interfere?

Answer 25

If two waves arrive at a point with a path difference equal to a whole number of wavelengths they will constructively interfere- Their phase difference will be on or a multiple of 2Pi

Question 26

What is Constructive Interference?

Answer 26

When two waves combine together in anti phase making them cancel out resulting in a quiet spot

Question 27

What causes destructive interference?

Answer 27

If two waves arrive at a point with a path difference of a half wavelength they’ll destructively interfere their phase difference would be Pi or A multi or of (n2Pi - Pi)

Question 28

What’s necessary for an observable interference patterns?

Answer 28

You need a coherent waves with a constant phase relationship

Question 29

What is the Principle of Superposition of Waves

Answer 29

the total displacement of a wave is equal to the sum of the displacements of two or more coherent waves

Question 30

Thomas Young Double Split

Answer 30

• Monochromatic Light - Produced by laser or sodium lamp• Very narrow skits to diffract light and create 2 coherent rays • Light from the slits superpower to create an interference patternConclusion • Bright fringes occur when the waves have traveled an integer number of whole wavelengths further than the other and so arrived completely in phase (constructive interference)• Dark fringes occur where one of the waves has a path difference of a half wavelength further than the other and so arrives in anti phase and destructively integers

Question 31

What is a stationary wave?

Answer 31

A stationary wave is the result of the superposition of two waves of the same wavelength and frequency when travelling in opposition directions • They store energy they don’t transfer it

Question 32

How are stationary waves produced?

Answer 32

1) Reflection of a progressive wave from a fixed end2) 2 progressive waves being sent from opposite directions3) Progressive waves travel from centre and are reflected from both ends

Question 33

Progressive Wave

Answer 33

• Amplitude - All parts of the wave between a pair of nodes are in phase and on different sides they are in anti phase • Wavelengths - Minimum distance between two adjacency points in an oscillating phase • Phase Difference - The phase changes across one complete cycle of the wave • Energy transfer - Transferred in the direction of the wave

Question 34

Stationary Wave

Answer 34

• Amplitude - Max amplitude at the antinode and then drops to zero at the nodes• Wavelength - Twice the distance between adjacent nodes - Equal to the wavelength of the waves that created it• Phase Differences - All parts of the wave have the same amplitude (assuming no energy loss to surroundings)• Energy transfer - No net energy transfer