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InterviewSolution
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An electric dipole consists of charges `pm 2.0 xx 10^(8) C` separated by a distance of `2.0 xx 10^(-3)` m. It is placed near a long line charge of linear charge density `4.0 xx 10^(-4) C m^(-1)` as shown in figure (30-W4), Such that the negative charge is at a distance of `2.0 cm from the line charge. Find the force acting on the dipole. A. 7.2 N towards the line chargeB. 6.6 N away from the line chargeC. 0.6 N away from the line chargeD. 0.6 N towards the line charge. |
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Answer» Correct Answer - D The electric field at a distance r from the line charge of linear density `lamda` is given by `E=lamda/(2piepsilon_(0)r)` Hence, the field at the negative charge, `E_(1)=((4.0xx10^(-4))(2xx9xx10^(9)))/0.02=3.6xx10^(8)NC^(-1)` The force on the negative charge, `F_(1)=(3.6xx10^(8))(2.0xx10^(-8))=7.2N` towards the line charge Similarly, the field at the positive charge, i.e., at r = 0.022 m is `E_(2)=3.3xx10^(8)NC^(-1)`. The force on the positive charge, `F_(2)=(3.3xx10^(8))xx(2.0xx10^(-8))=6.6N` away from the line charge. Hence, the net force on the dipole = 7.2N - 6.6N =0.6N towards the line charge |
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