A solid spherical conductor of radius R has a spherical cavity inside it (see figure). A point charge q is placed at the centre of the cavity. (a) What is the potential of the conductor? (b) If the charge q is shifted inside the cavity by a distance `Deltax`, how does the potential of the conductor change? (c) How does your answer to the question (a) and (b) change if the cavity is not spherical and the charge q is placed at any point inside it (see figure) (d) Draw electric field lines in entire space in each case. In which case all field lines are straight lines