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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).
Options
(a) B² / 2VE²
(b) 2VB² / E²
(c) 2VE² / B²
(d) E² / 2VB²
Correct Answer:
E² / 2VB²
Explanation:
For no deflection of beam, eE = evB ⇒ v = E/B
Also, 1/2 mv² = eV ⇒ v = E/B
e/m = v² / 2V = E² / 2VB²
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Topics: Dual Nature of Matter and Radiation
(150)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- A ball is projected upwards from the foot of a tower. The ball crosses the top
- The ionisation potential of hydrogen-atom is -13.6 eV. An electron in the groundstate
- Two cars A and B moving with same speed of 45 km/hr along same direction.
- The electric potential at a point in free space due to a charge Q coulomb is Q x 10¹¹ v
- Two charged particles have charges and masses in the ratio 2:3 and 1:4 respectively.
Topics: Dual Nature of Matter and Radiation (150)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
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