1 (a) State one of Kirchhoff's laws for electrical networks and state the physical principle as ple associated with the law stated. 2 Marks ( b) For the circuit shown in Fig 1.1, find the current flowing in each 8 Marks branch of the circuit. 80 6V 20V Fig 1.1 2 (a) Fig 2.1 shows a glass lens of refractive index 1.50, having a convex surface of radius 20cm and a concave surface of radius 40cm. Compute the focal length of the lens and state whether it is converging or diverging. 4 Marks 20cm 40cm Fig 2.1 (b) An object 1cm high is placed upright on the principal axis 40cm to the left of the lens shown in Fig 2.1. (1) Find the position of the image formed by the lens. State the nature of the image. (iii) Find the height of the image. 6 Marks2 Marks 3 ( a ) Define mass number and atomic number. 107 ( b ) The nucleus of an atom of silver is represented as 47 Ag. State the number of protons and the number of neutrons in the nucleus of this atom. ii) Given that ro = 1.2 x 10" m, calculate the radius of the silver nucleus. iii) Given that the mass of the silver nucleus is 106.879288u, calculate its binding energy. 8 Marks Additional Information: Mass of Proton: 1.007825u Mass of Neutron: 1.008665u 1 Atomic mass unit 1(u): 931 MeV