Two non conducting circular rings A and B, each of radius a = 30 cm are placed coaxially with their axes horizontal in a uniform electric field E = 1 0 5 NC − 1 directed vertically upwards as shown in

Question

Two non conducting circular rings A and B, each of radius $a = 30 cm$ are placed coaxially with their axes horizontal in a uniform electric field $E = 1 0^{5} NC^{- 1}$ directed vertically upwards as shown in figure. Distance between centres of these rings A and B is h=40 cm. Ring A has a positive charge $q_{1} = 10 μ C$ while ring B has a negative charge of magnitude $q_{2} = 20 μ C$ . A particle of mass $m = 100 gm$ and carrying a positive charge $q =$ $10 μ C$ is released from rest at the centre of the ring A. The velocity when it has moved a distance of 40 cm is (g $= 10 m / s^{2}$ )

TestHub · Accepted Answer

The weight of particle is balanced by external electric field force.

$U_{1} = U_{0} + \frac{Kq q _{1}}{a} \frac{Kq ( - q _{2} )}{a ^{2} + h ^{2}} U_{2} = U_{0} + \frac{Kq q _{1}}{a ^{2} + h ^{2}} + \frac{Kq ( - q _{2} )}{a} U_{1} = U_{2} + \frac{1}{2} mv^{2} v = 62 m / s$

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