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 v_m is the maximum velocity of emitted electron.
If V is the stopping potential,
Where v_m 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

λ_min = hc/eV
(b)Mosley’s law
Frequency (say K_α like x-ray)
(here a is constant)
b = 1 for K_α 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 =