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Two charges respectively of +3.2xx10^(-19) coublem and -3.2xx10^(-19) coulomb are separated by a distance of 2.4xx10^(-10)m . This dipole is placed in a homogeneous electric field of 4.0xx10^(5)V//m . Find (i) Electric dipole moment (ii)The maximum moment exerted on the dipole by the electric field. (iii)The energy necessary for rotating the dipole from equilibrium position to 180^(@). |
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Answer» Solution :(i)The electric dipole moment `P=qxx21` `P=3.2xx10^(-19)xx2.4xx10^(-10)` `P=7.68xx10^(-29)`coulomb `xx` meter (ii)The moment of the couple ACTING on the dipole `TAU=pEsintheta` for MAXIMUM moment `theta=90` `tau=PE` `=7.86xx10^(-29xx4.0xx10^(5)` `=31.44xx10^(-24)` `tau_("max")=3.14xx10^(-23)`newton `xx` meter (iii)Potential energy of the dipole `U=-PEcos theta`. In theposition of equilibrium `theta=0` `thereforeU=-PE` `U=-7.86xx10^(-29)xx4xx10^(5)` `=-3.14xx10^(-23)J` The energy Spent in rotating the dipole from `theta=0" to "theta=180^(@)`. `W=U_(180)-U_(0)` `=-PECos180-(-(PECos0)` `=PE+PE` `=2PE` `=2xx7.86xx10^(-29)xx4xx10^(5)` `=6.28xx10^(-23)J` |
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