An electron of charge 1.60 x 10\(^{-19}\) C is accelerated under a potential difference of 1.0 x 10\(^5\) V. Calculate the energy of the electron in joules.

The uncertainty in determining the duration during which an electron remains in a particular energy level before returning to the ground state is 2.0 x 10\(^{-9}\)s. Calculate the uncertainty in determining its energy at that level. (\(\frac{h}{2 \pi}\) = h = 1.054 x 10\(^{-34}\)Js)

(a) What is a vector quantity?

(b) Three vectors 3 ms\(^{-1}\) N 45° W, 12 ms\(^{-1}\)W and 5 ms\(^{-1}\)S act at a point.

(i) Sketch a vector diagram to illustrate the given information.

(ii) Calculate the resultant of the vectors.

(c) In a laboratory experiment to determine the force constant of a spiral spring, the mass or, the spring was varied and the corresponding extensions were measured and recorded as shown in the table below.

(i) Copy and complete the table. (Take g = 10 ms\(^{-2}\))

(ii) Plot a graph with weight, W, on the vertical axis and extension, e, on the horizontal axis.

(iii) Using the graph, determine the force constant of the spring.

(iv) Determine the natural length of the spring if its length was 38.0 cm when loaded with 250 g mass.

(a)(i) State two advantages of alcohol over mercury as a thermometric liquid.

(ii) When the bulb of a thermometer is placed in a beaker of hot water, the level of the mercury first falls and then rises gradually. Explain this observation.

(b) List two factors, other than temperature, that affect the rate of evaporation of a liquid.

(b) A block of lead of mass 100 kg in a crucible and at a temperature of 40 °C was placed in an electric furnace rated 10 kW. If the melting point of lead is 320 °C, calculate the:

(i) quantity of heat required to heat the lead to its melting point;

(ii) additional heat energy required to melt the lead;

(iii) time taken to supply this additional energy. (Specific heat capacity of lead = 120 Jkg\(^{-1}\) K\(^{-1}\) (Specific Idtent heat of fusion lead = 2.5 x 10\(^{4} JK^{-1}\))

(d) State two precautions necessary in an experiment to determine the specific latent heat of vaporization of water.

(a)(i) What is an eclipse?

(ii) List the three types of eclipse.

(b) A student in a lecture theatre can read from the board clearly but requires a pair of spectacles to read from a book.

(i) What eye defect has this student?

(ii) What type of lens is needed to correct the eye defect?

(iii) The focal length of the lens used to correct this defect is 10cm. Calculate the power of the lens.

(c) A car B moves towards a stationary car A. If B produces an ultrasonic sound at a point and it takes 5.6 x 10\(^{-3}\)s for a beep to be heard in B, calculate the distance between the two cars at that instant. (Speed. sound in air = 340 ms\(^-\))

(d) The image of an object is located 9 cm behind a convex mirror. If magnification produced is 0.6, calculate the focal length of the mirror.