K.C.S.E Physics Q & A - MODEL 2013PP2QN019
​(a) Figure 14 shows an E shaped steel block being magnetized by a current through two coils in series.
​On the figure, indicate
(i) the north and south poles of the resulting magnet (ii) the complete magnetic field pattern between the poles. (b) Figure 15 shows the permanent magnet made in part (a) above. 
​A coil wound loosely on the middle limb is connected in series with a low voltage a.c. and a switch. State and explain the observation made on the coil when the switch is closed.
(c) In a simple cell, the zinc plate gets negatively charged and the copper plate gets positively charged. (i) Name the electrolyte in the cell. (ii) Explain how: (I) Zinc gets negatively charged. (II) Copper gets positively charged (iii) State what constitutes the current when a wire is used to connect the zinc plate and the copper plate externally.
answers
​(b) coil moves to and fro
force on coil varies direction as current varies indirection. (c) (i) dilute sulphuric acid (ii) (I) Zinc ions go into acid leaving electrons on the plate (Il) Give up electrons to discharge hydrogen Ions. (iii) Electrons flow from zinc plate to the copper plate.
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K.C.S.E Physics Q & A - MODEL 2013PP2QN018
​(a) Figure 11 shows plane light waves in air incident on a convex lens whose principal focus is F, the waves move past point G.
​Complete the diagram to show the pattern of the emergent waves between the lens and point G.
(b)Figure 12 shows crests of circular water waves spreading from two points A and B due to a vibrator. C and D are points on the surface of the water. 
​Given that the amplitude of each wave is 5 cm, state with a reason the amplitudes of the waves at point:
(i) C; (ii) D. (c) Figure 13 shows a standing wave formed when a string of length 1 .5 m stretched between two supports is plucked in the middle. 
​(î) Explain how the standing wave is formed.
(ii) Determine the wavelength of the standing wave.
answers
(b) (i) 0 cm - trough and crest interference
(ii) +10 - crest and crest interference (c) (i) Waves produced are reflected at the fixed ends. Incident and reflected waves interfer constructively at antinodes and destructively at nodes. 
K.C.S.E Physics Q & A - MODEL 2013PP2QN017
(a) Figure 9 shows a cathode ray tube in which a beam of electrons is cast on the screen.
​(i) state how the electrons are produced in the tube.
(ii) state how the electron beam is detected. (iii) State the reason for having a variable potential difference (p.d.) at the: (I) grid; (II) anodes. (b) Figure 10 shows the waveform of a signal applied at the y-plates of an oscilloscope whose time-base is switched to the scale of 2 milliseconds per centimeter. 
​Determine:
(i) the period of the signal; (ii) the frequency of the signal.
ANSWERS
(a) (I) Thermionically by cathode
(ii) causing fluorescence on screen (iii) (i) control brightness of fluorescence (ii) to focus the electron beam 
K.C.S.E Physics Q & A - MODEL 2013PP2QN16
​(a) Two points A and B have a potential difference of V volts. Q coulombs of charge flow between A and B for t seconds. Determine:
(i) the electrical energy transformed between the two points in terms of Q. (ii) the power transformed in terms of Q and t. (iii) show that the power transformed is given by P = IV. 
​(b) The lighting circuit in a house has 20 lamps each rated 60 W, 240 V. Determine whether a fuse rated 4 A can be used in the circuit when all the lamps are put on.
answers
K.C.S.E Physics Q & A - MODEL 2013PP2QN15
​(a) Explain how a positively charged electroscope gets discharged when the cap is touched with a finger.
(b) Figure 7 shows capacitors A and B connected in series with a battery of e .m .f 4 V. 
​Determine:
(ï) the effective capacitance of the circuit. (ii) the quantity of charge in capacitor A. (iii) the quantity of charge in capacitor B. (c) Figure 8 shows an isolated negative point charge Q. 
​On the figure. sketch the electric field pattern around the charge.
answers
​(a) Negative charges flow from earth to cap.
Negative charge neutralizes the positive. 
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M.A NyamotiMy passion is to see students pass using right methods and locally available resources. My emphasis is STEM courses |
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