Question Library

State three ways of increasing the rate of cooling of a cup of hot tea.

(a) What is doping in a semi conductor? (b) Draw the symbol for OR gate.

(a) Write the de Broglie equation. (b) Explain the significance of the equation.

(a) (i) Define uniform acceleration. (ii) Write an equation that relates linear velocity, angular velocity and radius of path in circular motion. (b) Two forces 30 N and 40 N act at right angles to each other. Determine by scale drawing, the magnitude and direction of the resultant force,.using a scale of 1 cm to 5 N. (c) Explain why ships are usually refilled with sand and water after they have been emptied of their cargo. (d) A crate of drinks of mass 20 kg is placed on a plane inclined at 30^\circ to the horizontal. If the crate slides down with a constant speed, calculate the: (i) co-efficient of kinetic friction; (ii) magnitude of the frictional force acting on the crate. [ g = 10 ms\(^{-2}\)]

(a) Define specific latent heat of vaporization. (b) (i) What are renewable energy sources? (ii) List four renewable energy sources. (c) Explain why tomatoes keep longer when kept in a moist jute bag in a clay pot. (d) A box has a volume of 0.28 m\(^3\) and is 70% filled with iron fillings at 25^\circC. Calculate the: (i) total mass of the iron fillings; (ii) energy required to melt 10% of the iron fillings. [Density of iron = 8.00 x 10\(^3\) kgm\(^{-3}\); specific latent heat of fusion of iron = 1.38 x 10\(^5\) Jkg\(^{-1}\), specific heat capacity of iron = 460 Jkg\(^{-1}\) k\(^{-1}\), melting point of iron = 1500^\circC] 10.

(a)(i) what is resonance? (ii) State two eXwilples of resonance. (iii) Differentiate between loudness and intensity of sound. (b) When a ray is refracted through a rectangular glass prism, which of the following properties of the ray will change? Wavelength, frequency and speed. (c) (i) Copy the diagram above in your answer booklet. (iii) On the copied diagram, sketch the pattern of the waves immediately after passing through the opening. (d) A diverging lens of focal length 18.0 in is used to view a shark that is 90.0 in away from the lens. If the image formed is 1.0 m long, calculate the: (i) image distance; (ii) length of the shark.

(a) Define:(i) the coulomb; (ii) resistance. (b) State the three effects of an electric current. (c) State the standard international colour convention for the insulating material covering the following electrical wires in a three-pin plug: (i) live; (ii) neutral; (iii) earth. (d) A water melon of mass 5.0 kg is suspended on a uniform rod of mass 4.0 kg and 4.0 in long as illustrated in the diagram above. If the rod is in equilibrium by the action of the force between the charges +q and -q, calculate the: (i) anti-clockwise moment; (ii) value of q. [ g = 10 ms\(^{-2}\)]

(a) Define nucleon number (b) A radioactive isotope of Americium (Am —241) decays into a nucleus of Neptunium (Np — 237) and an alpha (\(\alpha\)) particle as shown in the nuclear equation below. \(^{241}_{95}Am\) \(\to\) \(^{237}_{c} + ^b_a \alpha\) (i) State the number of neutrons in the nucleus of Americium — 241. (ii) Determine the values of a,b and c. (c)(i) Why are y-rays not deflected by electromagnetic field? (ii) State two properties of gamma rays that make them suitable for sterilizing medical equipment. (d) A sample of radioactive substance was found to be left with h of its initial count rate after 110 years. Calculate its decay constant.

You have been provided with a resistance box, a voltmeter, a key, a battery, and other necessary materials. Connect the circuit as shown in the diagram above. With the key K closed, read and record the voltmeter reading \(V_0\). Set the resistance R in the resistance box equal to I\(\Omega\). Close the key, read and record the potential difference V on the voltmeter. EvaluateR\(^{-1}\) and V\(^{-1}\) . Repeat the procedure for five other values or R = 2\(\Omega\), 3\(\Omega\), 4\(\Omega\), 5\(\Omega\) and 6\(\Omega\). Tabulate your readings. Plot a graph with V\(^{-1}\) on the vertical axis and R on the horizontal axis. Determine the slope, s, of the graph and the intercept, C, on the vertical axis. Evaluate c\(^{-1}\) State two precautions taken to obtain accurate results. (b)i. Define the potential difference between two points in an electric circuit. ii. Explain why the emf of a cell is greater than the p.d. across the call when it is supplying Current through an external resistance.

You are provided with a retort stand, boss head, clamp, stopwatch, slotted weights, hanger, grooved pulley, thread, measuring tape, and other necessary materials. i. Measure and record the radius R of the pulley. ii. Setup the apparatus as illustrated in the diagram above, such that the clamp is 1.5 m above the floor. iii. Tie one end of the thread to the pulley. iv. Tie the other end of the thread to the hanger. v. Slot a mass m= 50 g on the hanger. vi. Wind the thread around the groove of the pulley until the base of the hanger is at a height h = 1.4 m above the floor. Maintain this height h for every other value of m through out the experiment. vii. Release the mass to unwind the thread. viii. Determine and record the time t taken by the mass m to reach the floor. ix. Evaluate t\(^{2}\) x. Also evaluate a =\(\frac{2h}{t^{2}}\),T = \(\frac{m}{1000}\) (10 - a) and \(\propto\) = \(\frac{a}{R}\) xi. Repeat the procedure for four other values of m = 70 g, 90 g, 110 g and 130 g xii. Tabulate your readings. xiii. Plot a graph with \(\propto\) on the vertical axis and T on the horizontal axis. xiv. Determine the slope s, of the graph. xv. Evaluate I = \(\frac{R}{s}\). xvi. State two precautions taken to obtain accurate results. (b)i. Define centripetal force ii. An object drops to the ground from a height of 2.0 m. Calculate the speed with which it strikes the ground. [g=10 ms\(^{-2}\)]

You are provided with a triangular glass prism, four optical pins, and other necessary materials. Place the triangular glass prism on a drawing paper and draw its outline UMR. Remove the prism. Measure and record the value of the angle at U. Draw a normal to the line UM at N. Also, draw another line TN to the normal such that \(\phi\)-60. Fix two pins at \(P_1\) and \(P_2\). Replace the prism and fix two other pains at \(P_3\), and \(P_4\), such that the pins appear to be in a straight line with the images of the pins at \(P_1\) and \(P_2\), when viewed from the side UR. Remove the prism. Join points \(P_3\), and \(P_4\), producing the line to meet TN produced at Z. Draw the normal XY. Measure and record the angle of emergence e and that of deviation d. Repeat the experiment with \(\phi\) = 55^\circ, 50^\circ, 40^\circ and 35^\circ. In each case, measure and record the Corresponding values of e and d. Tabulate your readings. Plot a graph with d on the vertical axis and e on the horizontal axis starting both axes from the origin (0.0) Join your points with a smooth curve. From your graph, obtain the minimum deviation \(d_m\) and the corresponding angle of emergence \(e_m\) . Hence, calculate the refractive index n of the prism using the formula: n = \(\frac{sin (\frac{d_{m}+U}{2})}{sin{(\frac{u}{2})}}\) State two precautions taken to obtain accurate results. Attach your traces to your answer booklet. (b)i. State the conditions necessary for total internal reflection of light to occur. ii. The critical angle for a transparent substance is 39^\circ. Calculate the refractive index of the substance.

You have been provided with a resistance box, a voltmeter, a key, a battery, and other necessary materials. Connect the circuit as shown in the diagram above. With the key K closed, read and record the voltmeter reading \(V_0\). Set the resistance R in the resistance box equal to I\(\Omega\). Close the key, read and record the potential difference V on the voltmeter. EvaluateR\(^{-1}\) and V\(^{-1}\) . Repeat the procedure for five other values or R = 2\(\Omega\), 3\(\Omega\), 4\(\Omega\), 5\(\Omega\) and 6\(\Omega\). Tabulate your readings. Plot a graph with V\(^{-1}\) on the vertical axis and R on the horizontal axis. Determine the slope, s, of the graph and the intercept, C, on the vertical axis. Evaluate c\(^{-1}\) State two precautions taken to obtain accurate results. (b)i. Define the potential difference between two points in an electric circuit. ii. Explain why the emf of a cell is greater than the p.d. across the call when it is supplying Current through an external resistance.

The filter in the cigarette reduce the nicotine construct by

Which of these require crystallization most?

Iron is often galvanized in order to