Atomic Theory of matter :-
According to this theory , atom is the ultimate particle of matter , also
known as Dalton’s Atomic theory (1808).
Cathode ray discharge tube experiments: -
1. Cathode
rays start from cathode and move toward anode.
2. These
rays are not visible but there behaviour can be observed with fluorescent or
phosphorus sent material.
3. In
the absence of magnetic or electric field these travels in strait lines
4. In
the presence or magnetic or electric field the behaviour of cathode rays in similar
TO Negatively charged particles
which suggest that these rays contain negatively charge particles called
electron
5. Cathode
rays (electrons) do not depend on the martial
of the electrode and nature of the gas
tin the tube so electro us are basic constituent of all atoms.
Charge (e) to mass (me) ratio of electron
ð Measured
by J. J. Thomson (1897).
ð By
using cathode ray tube ; applying electrical & magnetic field perpendicular
to each other also perpendicular to path of electrons.
ð He
proposed deviation of particles from
their path in presence of magnetic or electrical field depend upon the
following
1. Magnetic of – ve charge
on particle
i.e.
it magnitude of charge on particles is greater than interaction with magnetic
or electric field is greater so deflection is also grater.
2. Mass of
particles
i.e.
particle is lighter then deflection is greater.
3. Strength of magnetic or electric field.
i.e. it strength of
magnetic field or voltage at electron is
increases then deflection of e-
also increases
=> value of e/me =
1.758820× 1011 C kg-1
Charge of electron
=> Determine
by R. A. Millikan
=> By
oil drop experiment (1906-1914)
=> Charge
on e- = -1.6× 10-19
C
=> Present
accepted value , e- = -1.6022× 10-19 C
Mass of electron
From charge on e- & e/me
We get,
Me = 9.1094
´
10-31 kg
 to mass (me) ratio of electron){kind=link}