# Modern Physics

Published date: 25 Jun 2021 # Modern Physics

Modern physics is a branch of physics that deals with the post-Newtonian concepts in the world of physics based on the two breakthroughs of the 20th century.

## Electron

The charge of an electron (e) is given as e=-1.6×10-19 c. The mass of an electron is given as me=9.1×10-31 kg.
The specific charge is the ratio of charge to the mass of an electron.
∴ specific charge( e/me)=1.73×1011 c/kg

# Photons

The charge of a portion (e) is 1.6×10-19 candy mass is MP=1.6*10-27 kg.
∴ specific charge (e/mp)=(1.6×10^(-19))/(1.6×10^(-27) )=9.58×10-7 c/kg
Compare specific charge of electron and proton we know.   E=V/d [∴ r=d is the distance between +ve and -ve plate]
Quantization of charge is charged present in a body (Q) equal to integral (±n) multiple of a basic unit of charge € is known as quantization.
Q=±ne Let us consider a beam of electrons is projected in between two plates ‘p’ and ‘Q’ as shown in the figure. Let ‘v’ and’ be potential different and distance between two plates.
Now, considering the horizontal motion of electrons when electrons are parallel to the plates.
Then,  Here,
e=Charge of electron
m=mass of electron
v=Velocity of electrons
d=distance of two plates
Hence, equationn IV is equation of parabola so, the motion of electrons in the electrics field is parabolic. TT Let US Consider an electrons beam moving horizontally with speed ‘V’ Which enters a uniform magnetic field of magnitude B acting perpendicular to the distance of motion shown in the figure.

From figure,
Force acting on it,
F=BeV I
If the magnitude field is uniform the force is constant in magnetic and the beam travels in a circle in a circle of radius ‘r’ provides a centripetal force.
These are the conceptual notes of Modern Physics.