Q. 223.9( 7 Votes )
An electron gun w
Answer :
Given:
Potential at collector, V = 100V
Magnetic field strength, B = 2.83 × 10-4 T
Radius of orbit traced by electron, r = 12.0 cm
Let specific charge (i.e. e/m) = K
Kinetic energy of an electron is given by:
KE = = eV
→ v = …(1)
Where,
M = mass of electron
v = velocity of electron
e = charge of electron
V = potential difference (accelerating potential)
We also know that the bending is caused by the magnetic field,
So we can write,
Magnetic force = centrifugal force
e × v × B =
→ e × B =
→ v = …(2)
Where,
e = Charge on electron
v = velocity of particle
B = magnetic field strength
m = mass of electron
r = radius of trajectory
By equating (1) and (2) we can write,
.
→
By putting the values in above equation we get,
Hence the specific charge is 1.7 × 10-11 C Kg-1.
Rate this question :


(a) Estimate the
NCERT - Physics Part-IIAn electron gun w
NCERT - Physics Part-II(a) A monoenerget
NCERT - Physics Part-II