K.C.S.E Physics Q & A - MODEL 2008PP2QN13
The accelerating potential of a certain X-ray tube is increased. State the change observed on the X-rays produced.
ANSWER
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K.C.S.E Physics Q & A - MODEL 2008PP2QN12
​ A narrow beam of electrons in a cathode ray oscilloscope (CRO) strike the screen producing a spot. State what is observed on the screen if a low frequency a.c source is connected across the y-input of the CRO
ANSWER
K.C.S.E Physics Q & A - MODEL 2008PP2QN11
Figure 7 shows how rays from a distant and a near object are focused inside a human eye with a certain defect.
​Name the defect and state the cause of this defect.
Defect Cause of defect
ANSWER
K.C.S.E Physics Q & A - MODEL 2008PP2QN10
A heating coil is rated 100W, 240V. At what rate would it dissipate energy if it is connected to a 220V supply?K.C.S.E Physics Q & A - MODEL 2008PP2QN09
​Figure 6 shows a circuit in which a battery of negligible internal resistance, two resistors, a capacitor, a voltmeter and a switch are connected.
Giving a reason for your answer in each case, state the reading of the voltammeter, V, when the switch is
(i) Open V=………………………… Reason………………… (ii) Closed V=………………………… Reason………………. K.C.S.E Physics Q & A - MODEL 2008PP2QN08
​Figure 5 shows wavefronts approaching the boundary between two media.
​The speed of the waves in medium (2) is higher than that in medium (1). On the same diagram complete the figure to show the wavefronts after crossing the boundary.
K.C.S.E Physics Q & A - MODEL 2008PP2QN07
Figure 4 shows a hack-saw blade clamped horizontally on a bench and the free end is made to vibrate about the rest position.
​Determine the frequency of vibration of the blade.
K.C.S.E Physics Q & A - MODEL 2008PP2QN06
​ Figure 3 shows a flat spring made of iron clamped horizontally on the bench over a solenoid
When the switch is closed, the spring vibrates. Explain this observation.
answer
K.C.S.E Physics Q & A - MODEL 2008PP2QN05
​The diagram in figure 2 shows an object O placed in front of a converging lens. F and F are the principal foci for the lens.
The object is now moved along the principal axis until a virtual image is produced.
On the same diagram: (i) Draw the object O in the new position along the principal axis; (ii) Sketch rays to show formation of the virtual image K.C.S.E Physics Q & A - MODEL 2008PP2QN04
​ An un-magnetized steel rod is clamped facing North-South direction and then hammered repeatedly for some time. When tested, it is found to be magnetized. Explain this observation
answer
K.C.S.E Physics Q & A - MODEL 2008PP2QN03
​ You are provided with the following;
A cell and holder, a switch, a rheostat, an ammeter, a voltmeter and connecting wires. Draw a diagram for a circuit that could be used to investigate the variation of the potential difference across the cell with the current drawn from the cell. K.C.S.E Physics Q & A - MODEL 2008PP2QN02
A leaf electroscope A is charged and placed on the bench. Another uncharged leaf electroscope B is placed on the same bench and moved close to A until the caps touch. State and explain what is observed on the leaves of A and B.
answer
K.C.S.E Physics Q & A - MODEL 2008PP2QN01
​Figure 1 shows three point sources of light with an opaque object placed between them and the screen.
​Explain the nature of the shadow formed along B and C.
answer
BC - Total absence of light; umbra, completely dark
- Total darkness Rays are completed blocked from this region by the object K.C.S.E Physics Q & A - MODEL 2007PP2QN18
​(a) Figure 14 shows the features of a cathode ray tube
​(i) Name the parts labeled A and B
A …………………………………. B……………………………. (ii) Explain how the electrons are produced in the tube (iii) State two functions of the anodes (iv) At what part of the cathode ray tube would the time be connected? (v) Why is a vacuum created in the tube? (b) The graph in figure 15 was obtained on a cathode ray oscilloscope (CRO) screen when the output of an a.c generator was connected to the input of the CRO. The time- base calibration of the CRO was set at 20 milliseconds per centimeter and the y- gain at 5 volts centimeter.
​(i) Determine the pick voltage of the generator
(ii) Determine the frequency of the voltage On the same grid, redraw the graph for the same voltage when the time base calibration is set at 40 milliseconds per centimeter and y- gain at 10 volts per centimeter. (Show at least one complete cycle) K.C.S.E Physics Q & A - MODEL 2007PP2QN17
​(a) State Lenz's Law of electromagnetic induction
(b) Figure 13 shows a simple microphone in which sound waves from the person talking cause the cardboard diaphragm to vibrate
(i) Explain how a varying current is induced in the coil when the diaphragm vibrates
(ii) State two ways in which the induced current in (i) above can be increased (c) A transformer with 1200 turns in the primary circuit and 120 turns in the secondary circuit has its primary circuit connected to a 400V a.c source. It is found that when a heater is connected to the secondary circuit, it produces heat at the rate of 600w. Assuming 100% efficiency, determine the: (i) Voltage in the secondary circuit (ii) Current in the primary circuit (iii) The current in the secondary circuit K.C.S.E Physics Q & A - MODEL 2007PP2QN16
​(a) Figures 11 (a) and (b) show diagrams of the human eye
​(i) Sketch in figure 11 (a) a ray diagram to show shortsightedness
(ii) Sketch in figure 11 ( b) a ray diagram to show how a lens can be used to correct the shortsightedness (b) Figure 12 shows the features of a simple camer
(i) Name the parts labeled A and B
A ………………………………………. B ………………………………………. (ii) A still object is placed at a certain distance from the camera. Explain the adjustments necessary for a clear image of the object to be formed. (iii) State the functions of the shutter and the parts labeled A and B Shutter …………………………………………………………………. A………………………………………………………………………… B ……………………………………………………………………….. (c) A lens forms a clear image on a screen when the distance between the screen and the object is 80cm. If the image is 3 times the height of the object, determine. (i) The distance of the image from the lens (ii) The focal length of the lens K.C.S.E Physics Q & A - MODEL 2007PP2QN15
​(a) State Ohm's Law
(b) The graph in figure 9 shows the current – voltage characteristics of a certain device, X
(i) State with a reason whether the device obeys Ohm's law
(ii) Determine the resistance of the device, X, when the current through it is 60 mA. (iii) When the device, X is connected in the circuit below, the voltage across it is 0.70 V.
​Calculate the value of the resistance R.
(c) The cell in figure 10 has an e.m.f of 2.1 V and negligible internal resistance.
​Determine the
(i) Total resistance in the circuit (ii) Current in the circuit (iii) Reading of the voltmeter K.C.S.E Physics Q & A - MODEL 2007PP2QN14
​ You are provided with a diode, a resistor R, an a.c source of low voltage and connecting wires.
In the space provided, sketch the circuit diagram for a half – wave rectifier and indicate the terminals where the output voltage V0 may be connected. K.C.S.E Physics Q & A - MODEL 2007PP2QN13
​The following is part of radioactive decay series
​Determine the values of a and b
a = ……………………………………. b= ………………………………
answer
K.C.S.E Physics Q & A - MODEL 2007PP2QN11&12
​ The graph in figure 8 shows the variation of photoelectric current with applied voltage when a surface was illuminated with light of a certain frequency. Use the information in the figure to answer questions 11 and 12
​On the same axes, sketch the graph when light of higher intensity but same frequency is used to illuminate the surface.
Explain your answer in 11 above
K.C.S.E Physics Q & A - MODEL 2007PP2QN10
State what is meant by the term accommodation as applied to the human eye.
ANSWER
K.C.S.E Physics Q & A - MODEL 2007PP2QN09
​A heater of resistance R1 is rated P watts, V volts while another of resistance R2 is rated 2P watts, V/2 volts. Determine R1 / R2
K.C.S.E Physics Q & A - MODEL 2007PP2QN08
​In the circuit diagram shown in figure 7, the ammeter has negligible resistance
When the switch S, is closed, the ammeter reads 0.13 A.
​Determine the internal resistance of the cell
K.C.S.E Physics Q & A - MODEL 2007PP2QN07
​ Figure 6 shows a ray of light incident on the face of a water prism
​Sketch the path of the ray as it passes though the prism
Critical angle for water is 49 K.C.S.E Physics Q & A - MODEL 2007PP2QN06
​ Figure 5 (a) and (b), show wavefronts incident on barriers blocking part of the path.
​On the same figures sketch the wavefronts to show the behavior of the waves as they pass each barrier and after passing the barrier.
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