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QAIPMT-2010-Ph-2083: NEET 2010 Physics - Class 12 AIPMT-2010-Ph-2083 Solution: A beam of cathode rays is subjected to crossed electric (E) and …

A beam of cathode rays is subjected to crossed electric (E) and magnetic fields (B). The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by (Where V is the potential difference between cathode and anode)

Multiple Choice Options

A $\frac{B^2}{2VE^2}$
B $\frac{2VB^2}{E^2}$
C $\frac{2VE^2}{B^2}$
D $\frac{E^2}{2VB^2}$

Step-by-Step Verified Solution

Force on electron due to = Force on electron due magnetic field to electric field Bev = eE _ v = E B .......(1) If V is the potential difference between the anode and the cathode, then 1 2 m v 2 = eV _ e m = v 2 2 V .....(2) Substituting the value of v from equation (1) in equation (2), we get e m = E 2 2 V B 2

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