Question Library

In an A.C circuit, the ratio of r.m.s value to peak value of current is

Two resistors 5\Omega and 10\Omega are arranged first in series and later in parallel to a 24V source, the ratio of total power dissipated in the series and parallel arrangements respectively is

Use the diagram above as a guide to carry out the following experiment. Trace the outline ABCD of the rectangular glass prism on the drawing paper provided. Remove the prism. Select a point N on AB such that AN is about one-quarter of AB. Draw the normal LNM. Also, draw a line RN to make an angle \(\theta\) = 75^\circ with AB at N. Fix two pins at \(P_1\) and \(P_2\) on line RN. Replace the prism on its outline. Fix two other pins at \(P_3\) and \(P_4\) such that they appear to be in a straight line with the images of the pins at \(P_1\) and \(P_2\) when viewed through the prism from DC. (vi) Remove the prism and the pins at \(P_3\) and \(P_4\). Draw a line to join \(P_3\) and \(P_4\) Produce line \(P_4\) \(P_3\) to meet the line DC at O. Draw a line to join NO. Measure and record the values of MO and NO. Evaluate \(\theta\) = \(\frac{MO}{NO}\) and cos \(\theta\). Repeat the procedure for four other values of \(\theta\) = 65^\circ 55^\circ, 45^\circ, and 35^\circ. In each case, evaluate \(\theta\) and cos \(\theta\). Tabulate your readings. Plot a graph with cos \(\theta\) on the vertical axis and \(\theta\) on the horizontal axis. Determine the slope, s, of the graph. State two precautions taken to ensure accurate results (b)i. State Snell's law of refraction. ii. Calculate the critical angle for the glass prism used in the experiment above if its refractive index is 1.5.

A stone projected horizontally from the top of a tower with a speed of 4 ms\(^{-1}\) lands on the level ground at a horizontal distance of 25 m from the foot of the tower. Calculate the height of the tower. = 10 ms\(^{-2}\)]

(a) Explain diffusion. (b) Give one reason why the rate of diffusion is higher in gases than in liquids at the same temperature.

State: (a) the difference between plane polarized light and ordinary light; (b) two uses of polaroids.

(a). State: (a) two applications of electrolysis in an industry (b) one application of electrolysis in a school laboratory.

In fig. la and fig.1 b above, Ida and Wb represent the respective loads on a spring placedtiear a 30 cm rule, when in air and when in water: (a) Identify the force causing a shrink in the spring in fig.(b). (b) Given that the force constant of the spring is 2.0 x 10\(^{11}\) Nm\(^{-1}\), calculate the work done by the force in causing the shrink.

Explain why water in a narrow glass tube has a concave meniscus while mercury, in the same tube, has a convex meniscus.

State three methods of polarizing an unpolarized light

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^\circ 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. Mass M/g Weight W/N Extension e/cm 50 100 150 200 250 6.5 11.0 15.0 20.0 25.0 (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 ^\circC was placed in an electric furnace rated 10 kW. If the melting point of lead is 320 ^\circC, 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.