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A beam of electrons emitted from the electron gun G is accelerated by an electric field E. The area of cross-section of the beam remains constant. As the beam moves away from G, (a) the speed of the electrons increases (b) the current constituted by the beam increases (c) the number of electrons per unit volume in the beam increases (d) the number of electrons per unit volume in the beam decreases |
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Answer» Correct Answer is:(a, d) The speed of the electrons increases as they are accelerated. The current I remains constant, as the number of electrons emitted per second by the gun is constant. Now, I = Avne. As I, A and e are constant, while v increases, n must decrease. |
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