(b) A negative charge of -2.5 x 10% C is placed at coordinates (3.0, 0) m and a positive charge of 6.0 x 10* C is placed at (3.0, 4.0) m respectively. Calculate the electric potential due to these charges at point P with coordinate (0, 4.0) m. (3 marks) The electric potential at point P will (increase / decrease / remain the same) if the 6.0 x 10* C charge is replaced by a negative charge having the same magnitude. (1 mark) (C) Find the resistance per unit length of a gold wire with radius of 0.025 m. Given the resistivity.p of gold is 2.44 x 10 02.m