K.C.S.E Physics Q & A - MODEL 2010PP2QN19
(a) State the property of radiation that determines the number of electrons emitted when a radiation falls on a metal surface.
(b) Figure 15 is a graph of the stopping potential Vs against frequency in an experiment on photoelectric effect.
(i) What is meant by stopping potential?
(ii) Given that the stopping potential Vs is related to the frequency by the equation
K.C.S.E Physics Q & A - MODEL 2010PP2QN18
Figure 14a, is a diagram of a cathode ray tube. M and N are parallel vertical plates.
(a) When switch S is open, a spot is seen at the centre of the screen as shown in figure 14(b).
(i) State what happens to the spot when S is closed.
(ii) State what would happen to the spot if the potential difference across MN is increased.
(iii) State what would be seen on the screen if the battery is replaced with an alternating emf of:
(I) a low frequency of about 1 Hz;
(II) a high frequency of about 50Hz.
(b) Explain the process by which electrons are produced at F.
(c) State with a reason how the brightness of the spot can be increased.
(d) The accelerating voltage of the tube is 1000V and the electron current in the beam is 1 .5mA. Determine the energy conveyed to the screen per second.
K.C.S.E Physics Q & A - MODEL 2010PP2QN17
(a) Figure 12, shows an electrical circuit including three switches, S1, S2, S3, and three identical lamps L1, L2, L3. A constant potential difference is applied across X and Y.
(î) Other than L1, state the lamp that will light when S1 and S2 are closed.
(ii) How does the brightness of L1 in (i) above compare with its brightness when all the switches are closed?
(iii) Explain the observation in part (ii) above.
(b) Figure 13, shows a cell in series with a 3ohms resistor and a switch. A high resistance voltmeter is connected across the cell.
The voltmeter reads 1.5V with the switch open and 1.2V with the switch closed.
(i) State the electromotive force of the cell.
(ii) Determine the current through the 3ohms resistor when the switch is closed.
(iii) Determine the internal resistance of the cell.
(c) (î) Another resistor R is connected in series with the 3ohms resistor so that a current of 0.15A flows when the switch is closed. Determine the resistance of R.
K.C.S.E Physics Q & A - MODEL 2010PP2QN16
(a) Figure 10, shows an object placed in front of a converging lens of focal length 50mm
(i) On the same figure, draw a ray diagram showing the location of the image.
(ii) Use the ray diagram to determine the:
(1) image distance;
(iii) State the adjustment that should be done to obtain a larger virtual image using the same lens.
(iv) State one application of the arrangement in figure 10.
(b) Figure 11, shows a pin 60 mm long placed along the principal axis of the lens used in part (a). The near end of the pin is 80 mm from the lens.
Determine the length of the image.
K.C.S.E Physics Q & A - MODEL 2010PP2QN15
(a) Figure 8, shows a circuit that may be used to charge a capacitor.
(i) state the observation on the milliameter when the circuit is switched on:
(ii) explain the observation in (î) above.
(b) The circuit in figure 8 is left on for some time. State the value of p.d. across:
(j) the resistor R;
(ii) the capacitor C;
(c) sketch the graph of potential difference (V) across R against time.
(d) Figure 9 shows three capacitors connected to a 10V battery.
(î) the combined capacitance of the three capacitors;
(ii) the charge on the 5.0 uF capacitor.
FORM I - PHYSICS SYLLABUS
FORM II - PHYSICS SYLLABUS
FORM III - PHYSICS SYLLABUS
FORM IV - PHYSICS SYLLABUS
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