Data: k = 1/4TE. = 9.0 x 10' N m' C-2 (a) State Coulomb's law. [1] (b ) Three point charges are located at the corners of an equilateral triangle, as shown in Fig. 1.1. Calculate the magnitude and direction of the resultant electrostatic force on the -8 JC charge. [9] +7 UC 0.5 m -8 uc. . . .. - - - -0 +6 uC Fig. 1.1 2 (a) Define the term capacitance. [1] (b) For the circuit shown in Fig.2.1, find 6 UF 4 UF 12 V 3 UF Fig. 2.1 (i) the equivalent capacitance of the circuit. (ii) the charge on each capacitor. (iii) the p.d, across each of the capacitors. (iv) the total energy stored by the three capacitors. [9](a) (i) State the laws of refraction. [2] (ii) A beam of light travelling in air (n = 1.0) enters a block of flint glass (n = 1.63) at an angle of incidence of 50". Find the angle of refraction. [3] (b) An object 2.0 cm high is placed in an upright position 15.0 cm from a concave mirror whose focal length is 20 cm. Find the location and size of the image. [5]