Dawn of modern Physics Flashcards
Wein’s constant
2.9× 10^ -3 m.K
Stefen’s constant
5.67 × 10^-8 W/(m2.T-4)
En = nhf
plank’s theory discovered in 1900
plank’s constant
6.626 × 10^-34 J.s
This constant is as important as constant c speed of light.
Electromagnetic waves were first predicted by?
Maxwell
Electromagnetic waves were first produced by?
Hertz
Photoelectric effect phenomenon was discovered by?
Experiment for particle nature of light
Hertz
Particle nature of light was proposed by?
Max plank
Particle nature of light was proven, explained by?
Einstein
Plank received nobel prize in ?
1918 for discovery of energy quanta
Energy of gamma ray photons?
1 MeV
Energy of radiowave photons?
10^-10 eV
Relation between radio and gamma photons
10^16 radio photons = 1 gamma photon in energy
no of photons from power given?
n = P/E
= P/hf
Intensity ? (n
I = P/A I= P/ 4 π^2 (surface area)
Joule to eV conversion?
eV is the smaller unit
1 eV = 1.6 × 10^-19 J
1 J = 1/ 1.6× 10^-19 eV
E (in eV)= 1240 / wavelength (in nm)
E = hc / wavelength
stopping potential in photoelectric effect?
reverse (negative) potential at which current becomes zero. (V)
Max energy of electrons?
(1/2) mv^2 = V e
Threshold frequency and Cutoff wavelength?
Minimum frequency of light for photoelectric effect to occur.
Maximum wavelength of light for photoelectric effect to occur.
Work function?
Minimum energy required for electrons to escape the metal surface.
E = hf = work function + K.E (max)
hf = hf(threshold) + (1/2) mv^2
Explanation of photoelectric effect was given by ? in ?
Albert Einstein in 1905
Einstein was awarded nobel prize in?
1921
Light used for sodium, potassium, cesium coated silver oxide cathode in photocell?
Na, K = visible light
Cesium coated silver oxide = infrared light
Compton effect?
1923 Arthur H Compton.
X-rays bombarded on a Graphite target scattered with larger wavelength.
del lambda called COMPTON SHIFT is difference between their wavelengths.
compton shift = h/mc (1- cos theta)
here m is rest mass of electron.
Compton wavelength?
2.43×10^-12 m
compton shift at angle 90 degrees and 180 degrees?
compton shift = compton wavelength at 90 degrees
compton shift = 2 compton wavelength at 180 degrees
nobel prize for compton on?
1926
rest mass of photon?
0
mass of photon?
E/c^2 = hf/c^2 = h/c .lambda
momentum of photon?
E = pc p = E/c p = hf/c p= h/lambda
rest mass of electron or positron?
0.51 MeV
energy required for pair production?
more than 1.02 MeV
no. of photons, mass relation with lambda?
no of photons is directly proportional to lambda
mass inversely proportional to lambda
wavelength, frequency, velocity formulas ?
wavelength (nm) = 1240/ V
wavelength (angstrom) = 12400/V
Frequency = 2.4 ×10^14 V
Velocity = 3.5×10^5 (V)^1/2
