Q. 7 B4.2( 95 Votes )
Explain why two field lines never cross each other at any point?
An electric field line represents the direction in which a positive test charge would accelerate in if placed on the line. If two field lines intersect, then this will imply that the electric field intensity points to two directions at the same point. This is not possible.
Hence, two electric field lines will never cross each other.
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A particle having a charge of 2.0 × 10–4 C is placed directly below and at a separation of 10 cm from the bob of a simple pendulum at rest. The mass of the bob is 100g. What charge should the bob be given so that the string becomes loose?
(a) Describe briefly the process of transferring the charge between the two plates of a parallel plate capacitor when connected to a battery. Derive an expression for the energy stored in a capacitor.
(b) A parallel plate capacitor is charged by a battery to a potential difference V. It is disconnected from battery and then connected to another uncharged capacitor of the same capacitance. Calculate the ratio of the energy stored in the combination to the initial energy on the single capacitor.
(a) Derive an expression for the electric field at any point on the equatorial line of an electric dipole.
(b) Two identical point charges, q each, are kept 2m apart in air. A third point charge Q of unknown magnitude and sign is placed on the line joining the charges such that the system remains in equilibrium. Find the position and nature of Q.
Physics - Board Papers
Repeat the previous problem if the particle is displaced through a distance x along the line AB.