**Griffiths problems:**

1) | 4.7 | [5 pts] |

Hint: you can consider the interaction energy U as the integral over all space of the charge density rho(r) times the electrostatic potential V(r). If V(r) is slowly varying on the length scale that the charge distribution of the dipole rho(r) is varying, then one can do a Taylor series expansion of V(r) inside the integral. | ||

2) | 4.11 | [10 pts] |

3) | 4.20 | [10 pts] |

4) | 4.33 | [5 pts] |

5) | 4.35 | [10 pts] |

6) | 4.36 | [10 pts] |