(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%.

(a) Explain what is meant by photoelectric emission

(b) Draw a labelled diagram showing the structure of a simple type of a photocell and explain its mode of operation.

(c) State four applications of photoelectric emission.

(d) In a photocell, no electrons are emitted until the threshold frequency of light is reached. Explain what happens to the energy of the light before emission of electrons begins. State one factor that may affect the number of emitted electrons. 

(a)(i) Explain what is meant by a machine (ii) Define the terms: mechanical advantage, velocity ratio and efficiency as applied to a machine. Derive the equation connecting the three terms.

(b) Explain why the efficiency of a machine is usually less than 100%

(c) A screw jack whose pitch is 4.4mm is used to raise a body of mass 8000 kg through a height of 20cm. The length of the tommy bar of the jack is 70cm. If the efficiency of the jack is 80%, calcuate the: (i) velocity ratio of the jack; (ii) mechanical advantage of the jack (iii) effort required in raising the body, (iv) work done by the effort in raising the body \((g = 10ms^{-2};  \pi = \frac{22}{7}\))