Free KCSE Physics Topical Questions KNEC Standards

K.C.S.E Physics Q & A - MODEL 2004PP2QN07

12/7/2020

K.C.S.E Physics Q & A - MODEL 2004PP2QN07

a) i) What is photoelectric effect?
ii) You are provided with the following:
a photocell, a source uv light, a rheostat, a source of e.m.f, a milliammeter, a voltmeter and connecting wires. Draw a circuit diagram to show how photoelectric effect may be demonstrated in the laboratory.
b) In a photoelectric effect experiment, a certain surface was illuminated with radiation of different frequencies and the stopping potential determined for each frequency
Table 2 shows the results obtained.

(i) Plot the graph of the graph of stopping potential (y-axis) against frequency.
(ii) Determine Planks Constant, h, and the work function,of the surface given that eVs = hf- hfo where e= 1.6x 10^-19 coulomb and hf = 0(thita)fo is the lowest frequency that can cause photoelectric effect.
c) A surface whose work function = 6.4 x 10^-19 joules is illuminated with light of frequency 3.0 x 10 ¹⁵HZ
Find the maximum Kinetic energy of the emitted photoelectrons (Use the Value of H obtained in b(ii)

answers

K.C.S.E Physics Q & A - MODEL 2004PP2QN07

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K.C.S.E Physics Q & A - MODEL 2004PP2QN05

K.C.S.E Physics Q & A - MODEL 2004PP2QN04

K.C.S.E Physics Q & A - MODEL 2004PP2QN03

ii) A radioactive sample of half-life 130 days initially has 1.0 x 102c radioactive atoms. Determine the number of radioactive atoms that have decayed after 390 days.

K.C.S.E Physics Q & A - MODEL 2004PP2QN02

K.C.S.E Physics Q & A - MODEL 2004PP2QN01

K.C.S.E Physics Q & A - MODEL 2004PP1QN35&36

K.C.S.E Physics Q & A - MODEL 2004PP1QN34

The work function of a certain material is 3.2 3V. Determine the threshold frequency for the material. (1 electron Volt (eV)= 1.6 x10-19) and planks Constant h=6.62 x 10-34Js)

State the difference between hard X-ray and soft X-rays.

K.C.S.E Physics Q & A - MODEL 2004PP1QN32

K.C.S.E Physics Q & A - MODEL 2004PP1QN31

K.C.S.E Physics Q & A - MODEL 2004PP1QN30

K.C.S.E Physics Q & A - MODEL 2004PP1QN29

State the difference between X-rays and Gamma rays in the way in which they are produced.

K.C.S.E Physics Q & A - MODEL 2004PP1QN27

K.C.S.E Physics Q & A - MODEL 2004PP1QN26

K.C.S.E Physics Q & A - MODEL 2004PP1QN25

K.C.S.E Physics Q & A - MODEL 2004PP1QN24

K.C.S.E Physics Q & A - MODEL 2004PP1QN23

K.C.S.E Physics Q & A - MODEL 2004PP1QN21&22

K.C.S.E Physics Q & A - MODEL 2004PP1QN20

State the difference between mechanical and electromagnetic waves.

K.C.S.E Physics Q & A - MODEL 2004PP1QN18

K.C.S.E Physics Q & A - MODEL 2004PP1QN17

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ii) A radioactive sample of half-life 130 days initially has 1.0 x 10²c radioactive atoms. Determine the number of radioactive atoms that have decayed after 390 days.

The work function of a certain material is 3.2 3V. Determine the threshold frequency for the material. (1 electron Volt (eV)= 1.6 x10^-19) and planks Constant h=6.62 x 10^-34Js)