The dipole moment of the water molecule is 6.1x10^-30 C*m. In an electric field,
ID: 2049799 • Letter: T
Question
The dipole moment of the water molecule is 6.1x10^-30 C*m. In an electric field, a molecule with a dipole moment will tend to settle into an equilibrium orientation such that the dipole moment is parallel to the electric field. If disturbed from this equilibrium orientation the molecule will oscillate like a torsional pendulum. Calculate the frequency of small oscillations of this kind for a water molecule about an axis through the center of mass (and perpendicular to the plane of the three atoms) when the molecule is in an electric field of 2.0x10^6 N/C. The moment of inertia of the molecule about this axis is 1.93x10^-47 kg*m*m.Explanation / Answer
When the dipole moment is disturbed by an angle d from equilibrium position we get
a torque in the dipole and the equation becomes
2*q*E* d * x = I
so ^2 = (6.1*10^-30 * 2 * 10^6)/(1.93*10^-47)
on solving we get = 7.95 * 10^11
period of oscillation 2*/
on solving we get 7.9 * 10^-12 sec