Modern Physics Ch 2

We regard electrons as particles because they possess charge and mass we also interpret a moving electron as wave manifestation because 

they exhibit diffraction, interference, and polarization

how did we find out electrons act as waves

In the double-slit experiment, electrons fired one by one still form an interference pattern — a clear sign of wave behavior

the speed 𝑐 of electromagnetic waves in free space

𝜖0 is …………… of free space and 𝜇0 ……………….

the electric permittivity, is magnetic permeability

electromagnetic waves travel with the speed of

light

light consists of 

electromagnetic waves

X-ray frequency is from

10^-8 - 10^-12

destructive interference shows as , it’s wavelength is

dark line, odd number half wavelength

constructive interference shows as, it’s wavelength is?

bright line, integer number of wavelength

A Blackbody is 

an ideal body that absorbs all radiation incident on it, Regardless of frequency 

When metals get hot they radiate heat and light that is

EM energy

when body is in thermal equilibrium with it’s surroundings it absorbs radiation at the same rate as it……….. which walls are perfect reflectors of…………..

Emits it, standing EM waves 

Formula for blackbody radiation 

Oscilator energies

Actual average energy per standing wave 

Photoelectric effect is when

we direct light at metals after freq. ν₀ we see electrons emitting called Photoelectrons 

under critical frequency ν …………. emit

no electrons emit

energy of Photo-electrons range form

0 to max value that increase linearly with increase in freq.

Photoelectrons acquire kinetic energy by……….. which produces ……………..that can be measured 

Absorbing photon energy, Electric current 

on Photoelectric effect - Higher frequency of light result in

higher energy of Photoelectron

Photon energy =

hv

in photoelectric effect work function

Photo electric formula 

energy of incident photon can be calculated using

h*c/lamda

X-rays are? there wavelength range from

EM waves, 0.01 to 10 nm

in X-ray, The higher the accelerating voltage the

faster the electrons and shorter the wavelengths 

X-ray production formula

in X-ray ve is Kinetic energy =

hv_max =

In X-ray v_max =

c/λ_min

X-ray diffraction

compton effect in photo

Compton effect is 

scattering of electron by photon, Energy and momentum are conserved 

(Compton)The photon loses an amount of its energy in the collision

which is gained by the scattered electron as kinetic energy 𝐾

(compton) scattered photon has freq. …….. than incident photon

Lower

(compton) scattered photon has……. energy and ……… wavelength 

less energy, longer wavelength 

Wavelength in compton

compton effect in formula

Pair production

Photon materialize into an electron and a positron

Pair production cannot occur in

empty space it needs a nucleus to conserve momenutm

Pair production need a photon of atleast 

1.02 MeV any additional turns becomes kinetic energy for the electron and positron 

inverse of pair production ocures when

positron ids near an electron and two become one with lost mass becoming energy in form of two gamma rays

radiation intensity is

x absorber thickness is 

photon and gravity

Photon energy after falling thru hight H