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 . 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