K.C.S.E Physics Q & A - MODEL 1999PP2QN07
a) Figure 7 shows a photoelectric cell cirucuit:
The intensity of the light can be varied.
i) Describe how the circuit may be used to show how the current I varies with the potential difference V across the cell.
ii) Sketch on the same axis graphs of I versus V for three different values of light intensity E1E2 and E3 such that E3>E2>E1
b) Using a circuit similar to the one in figure 7. with the polarity of the batteries reversed, the frequency, of the light was varied at constant intensity. For each frequency, the potential difference was varied until the current was equal to zero. The value of this voltage, Vco was noted. The graph in figure 8 shows the relation between Vco and the frequency , of the incident light.Feom the graph, determine the:
i) Value of planks constant, h (charge an electron e = 1.6 x 10-19Colubomb)
ii) Work function, of the cathode surface of the cell . (Give your answers to 2 decimal places.)
FORM I - PHYSICS SYLLABUS
FORM II - PHYSICS SYLLABUS
FORM III - PHYSICS SYLLABUS
FORM IV - PHYSICS SYLLABUS
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