QUESTION 4 [10 MARKS] Three point charges Q/ = +2.00 /C, 02 = -6.00 #C and Q3 = 3.00 #C are arranged along a straight line as shown in Figure 2. Point P is the midpoint that located between O, and Or while point R is the midpoint that located between Oz and Q3. 5.00 m 3.00 m P R Figure 2 a) Calculate the electric potential at point P and point R. [6 marks] b) Find the work done in moving proton from point P to point R. [4 marks]