(a) Explain the terms reactance and impedance in an a.c circuit.

(b) A source of e.m.f. 240 v and frequency 50 Hz is connected to a resistor, an inductor and a capacitor in series. When the current in the capacitor is 10A, the potential difference across the resistor is 140V and that across the inductor is 50V. Draw the vector diagram of the potential difference across the inductor, the capacitor and the resistor. 
Calculate the (i) potential difference across the capacitor; (ii) capacitance of the capacitor; (iii) inductance of the inductor.

(a)(i) By means of a labelled diagram, describe the mode uf operation of a modern X-ray tube.

(ii) State the energy transformation which takes place during the operation.

(b) Explain the terms hardness and intensity as applied to X-rays

(c)(i) State three uses of X-rays

(ii) State one hazard of over-exposure to X-rays in a radiological laboratory, indicating two safety precautions. 

(a) Explain what is meant by the following statement. The specific latent heat of fusion of ice is \(3.4 \times 10^{5}Jkg^{-1}\).

(b) Describe an experiment to determine the specific latent heat of fusion of ice. State two precautions necessary to obtain an accurate result.

(c) Using the kinetic theory of matter, explain why ice can change to water at 0°C without any change in temperature. 

(a)(i) What is meant by resonance?

(ii) Outline the necessary steps taken in a simple experiment to illustrate top resonance

(iii) Explain why a vibrating tuning fork sounds louder when its stem is pressed against a table top than when held in air.

(b) Explain with the aid of diagrams, how a concave mirror could be used to: (i) Ignite a piece of carbon paper; (ii) produce an exact copy of a picture on a screen. 

(a) Draw a simple labelled diagram illustrating the principle of a step-down transformer and explain how it works

 (b) State three ways by which energy is lost in a transformer and how they can be minimized.

(c) If a transformer is used to light a lamp rated at 60W, 220V from a 4400V a.c. supply, calculate the; (i) ratio of the number of turns of the primary coil to the secondary coil in the transformer (ii) current taken from the main circuit if the efficiency of the transforme is 95%.