(a) Explain with the aid of a diagram how a converging lens could be used to : (i) ignite a piece of carbon paper ; (ii) produce an enlarged picture on a screen ; (iii) correct an eye defect.

(b) What is a mechanical wave? Describe with the aid of a diagram, an experiment to show that sound needs a material medium for transmission. 

State 3 characteristics of sound and mention the factor on which each depends.

(a) Explain what is meant by: (i) electric field intensity ; (ii) electric lines of force.

(b) Two similar but opposite point charges -q and +q each of magnitude \(5 \times 10^{-8} C\) are seperated by a distance of 8.0cm in vacuum as shown in the diagram below.

Calculate the magnitude and direction of the resultant electric field intensity E at the point P. Draw the lines of force due to this system of charges. [Take \(\frac{1}{4 \pi \varepsilon _{0}}\)]

(c)  

Calculate the following in the series circuit shown above: (i) reactance of the capacitor ; (ii) impedance of the circuit ; (iii)  current through the circuit ; (iv) voltage across the capacitor ; (v) average power used in the circuit.

(a) Define the apparent cubic expansivity of a liquid

(b)(i) Describe with the aid of a labelled diagram, an experiment to determine the apparent cubic expansivity of a liquid.

(ii) State two precuations that should be taken to ensure accurate results.

(c) A density glass bottle contains 44.25g of a liquid at 0°C and 42.02g at 50°C. Calculate the real cubic expansivity of the liquid. (Linear expansivity of glass = 1.0 x 10-5K\(^{-1}\))

(a) What is meant by dispersion of white light?

(b) State the colours in the spectrum of white light in ascending order of their wavelengths

(c) Which colour is deviated.

(i) least

(ii) most?

(d) Explain why white light is dispersed when it passes through a glass prism.

(e) Describe, with the aid of a labelled diagram, how a pure spectrum of white light can be produced on a screen.

(a) Explain what is meant by the statement: The capacitance of a parallel-plate capacitor is 2\(\mu\)F

(b) State: (i) three factors on which its capacitance depends

(ii) three uses of capacitors.

(c) Derive a formula for the energy W stored in a charged capacitor of capacitance C carrying a charge Q on either plate.,

(d) Two parallel-plate capacitors of capacitances 2\(\mu\)F and 3\(\mu\)F are connected in parallel and the combination is connected to a 50V d.c. source. Draw the circuit diagram of the arrangement and determine the:

(i) charge on either plate of each capacitor

(ii) potential difference across each capacitor

(iii) energy of the combinad capacitors.