A molecule of a substance has a permanent electric dipole moment of magnitude 10^–29 C m. A mole of this substance is polarised (at low temperature) by applying a strong electrostatic field of magnitude 10⁶ V m^–1. The direction of the field is suddenly changed by an angle of ${60}^0$. The heat released by the substance in aligning its dipoles along the new direction of the field is: (For simplicity, assume 100% polarisation of the sample).

1. 6 J

2. 8 J

3. 3 J

4. 4 J