Wave 1

Question 1

Progressive Waves

Answer 1

progressive waves transfer energy from one place to another, but not matter

Question 2

Phase difference

Answer 2

difference in displacement of a particle along a wave

Question 3

Using an osciliscope to determine wave frequency

Answer 3

the screen shows a graph of p.d against time for any signal fed to it.

Question 4

Timebase

Answer 4

horizontal squares on the oscilisope screen which represents a certain time interval eg 10ms/cm

Question 5

what is a wave profile

Answer 5

displacement distance graph

Question 6

wavefront

Answer 6

line joining points of the wave which are in phase.

Easier to think of as peaks of the wave.

Question 8

reflection

Answer 8

angle of incident = angle of reflection

wavelength and frequency is the same

Question 9

refraction

Answer 9

n1 sin θ1 = n2 sin θ2
where n is the refractive index
θ is the angle from the normal

n = c/v for em waves

velocity propotional to θ

n inversely propotional to θ

Question 10

partial reflection

Answer 10

when a wave reflect there’s always some reflection off the surface

Question 11

Diffraction

Answer 11

property unique to waves

occurs when passing through a gap or travel around an obstacle, and they spread out

when differacted speed, wavelength and frequency do not change

more diffraction occurs when the gap is about the same size as wavelength of the wave

Question 12

Polarisation

Answer 12

means particle ocsilate along one direction only

plane polarised whena wave is confined to one single plane

only transverse waves

Question 13

partial polarisation

Question 14

Intensity

Answer 14

intensity of a progresive wave is the radiant(radiation) power passing through a surface per unit area.

measured in W/m^2

I = P/A

Question 15

what is the power distnace r from a source

Answer 15

power spread uniformaly in all directions from a source.

so the area of the power would be of a sphere

I = P/A = P/( 4 π r^2 )

Question 16

Intensity and Amplitude

Answer 16

I ∝ A^2

Question 17

in the em spectrum why are there overlapse between x ray and gamma ray

Answer 17

they are classified by thier origin,

X rays are emitted from fast moving electrons whereas gamma rays are from unstable atomic nuclei

Question 18

polarising filters

Answer 18

polarising filters called polarisers can be used to polarise which only allows wave in one orientation to go through

Question 19

polarisation of light

Answer 19

two polarisers

first one polarises the light

second one (often called analyser) rotates and intensity decresases, at 90 degrees to the first intensity falls to zero.

Question 20

polarisation of microwaves

Answer 20

instead of using a polaroid filter a metal grille is used

Question 21

refractive index

Answer 21

n = c/v

Question 22

conditions for total internal reflection

Answer 22

light must be traving through a medium with higher refractive index as it stricks with one iwht a lower one

angle which it strikes needs to be ablove the critical angle

Question 23

formula for total internal reflection derivation

Answer 23

from snells law

n1 sin θ1 = n2 sin θ2

θ2 = 90 =>

sin θ1 = n2/n1

but its air outside so n2 is 1

sin θ1 = 1/n1

Question 24

determining refractive index of a material using critical angle