# Photoelectric Physics

### 1. Photoelectric Effect

(a)Einstein’s photoelectric equation where W is the photoelectric work function, v is the frequency of incident radiation, and vm is the maximum velocity of emitted electron.
If V is the stopping potential, Where vm is the maximum speed of ejection.
(b)Threshold frequency
v0 = W/h, (c)Energy of photon
E ### 2. Bohr's Atomic Model

(a)Radius of the Bohr orbit (b)Energy of electron in the nth orbit
E (c)Velocity of electron (d)Spectral series
wave number, where, (e)Ionization energy of hydrogen atom
I.E = –13.6 eV
Energy of hydrogen atom in the ground state = –13.6 eV
(f)The values of constants eV-nm (where ) (for electron)
Bohr magneton, (g)Series limits (for Balmer etc, in hydrogen atomic spectra) are calculated for transitions from n = ∞ state.

### 3. X-Rays

(a)Continuous X-ray
λmin = hc/eV
(b)Mosley’s law
Frequency (say Kα like x-ray) (here a is constant)
b = 1 for Kα line
(c)Bragg’s law
, where n = 1, 2 , 3 ,…………..
d is a lattice distance and θ is glancing angle

### 4. Nuclear Physics

(a)Law of radioactive decay , where λ is the decay constant, N0 the number of atoms at t = 0 and N, the number of atoms remaining after time t
Activity (unit is Becquerel)
Half life period, (b)Energy-mass equivalence
E = mc2
1 atomic mass unit = 931 MeV (denoted as a.m.u or u)
(c)Nuclear binding energy
E =  