MagnetismHard
Question
A beam of cathode rays is accelerated by a potential V and then subjected to crossed electric (E) and magnetic field (B). such that the beam is not deflected. The specific charge of the cathode rays is given by ?
Options
A.
B.
C.
D.
Solution
When a beam of cathode rays (or electrons) are subjected to cross electric (E) and magnetic (B) fields, the beam is not defined, if
Force on electron due to magnetic field = Force on electron due to electric field
Bev = eE
or, v =
...... (i)
If V is the potential difference between the anode and the cathode, then
∴
mv2 = eV
...... (ii)
Substituting the value of v from equation (i) in equation (ii), we get
Specific charge of the cathode rays
Force on electron due to magnetic field = Force on electron due to electric field
Bev = eE
or, v =
...... (i) If V is the potential difference between the anode and the cathode, then
∴
mv2 = eV ...... (ii) Substituting the value of v from equation (i) in equation (ii), we get
Specific charge of the cathode rays
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