Free KCSE Physics Topical Questions KNEC Standards

K.C.S.E Physics Q & A - MODEL 2019PP2QN19

15/10/2020

K.C.S.E Physics Q & A - MODEL 2019PP2QN19

(a) Define half life as used in radioactivity.
(b) Figure 13 shows a device used to detect radioactivity by forming tracks when air is ionised.

(i) State the name of the device shown.
(ii) State how air in the device gets ionised.
(iii) Describe how tracks are formed
(c) (i) State two factors that determine the speed of the photoelectrons emitted from a metal surface
(ii) The energy of a photon of light is 2.21 eV. (electronic charge is 1.6x10^-19C and planks constant h is 6.63x10^-34Js)
I. Express this energy in joules.
II. Determine the frequency of the light that produces the photon.

answers

(a) Half life is the time taken for half the number of nuclides initially present in a sample to decay
(b). (ii) Expansion closed chamber
(ii) Due to collisions between the molecules from the radiations source and the air molecules
(iii) When the piston is pulled down air expands hence cools.
(c)(i) The work function of the metal
Energy of incident radiation frequency/wavelength

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K.C.S.E Physics Q & A - MODEL 2019PP2QN12

31/7/2020

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K.C.S.E Physics Q & A - MODEL 2019PP2QN12

Uranium decays as shown below.

Name the particle X that is emitted during this decay.

answer

Apha particle

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Define radioactivity

29/7/2020

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K.C.S.E Physics Q & A - MODEL 2018PP2QN08

Define radioactivity

answer

Spontaneous disintegration of atomic nuclei by emission of radiations.

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K.C.S.E Physics Q & A - MODEL 2017PP2QN10

28/7/2020

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K.C.S.E Physics Q & A - MODEL 2017PP2QN10

Write an equation to show how an element ^A _Z X decay to element Y by emitting a beta particle.

answer

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K.C.S.E Physics Q & A - MODEL 2016PP2QN17

27/7/2020

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K.C.S.E Physics Q & A - MODEL 2016PP2QN17

When a radiation was released into a diffusion cloud chamber, short thick tracks were observed. State with a reason, the type of radiation that was detected.
(b)The half-life of an element X is 3.83 days. A sample of this element is found to have an activity rate of 1.6 x 10^3 disintegrations per second at a particular time.
Determine its activity rate after 19.15 days.
(c) State what is meant by an extrinsic semiconductor.
(d)Figure 11, shows a depletion layer in an unbiased p-n junction

State how a battery can be used to make the depletion layer narrower.
(e)Figure 12, shows an incomplete circuit of a full wave rectifier.

(i) Draw in the figure two more diodes to complete the circuit should be obtained.

answers

(a)Alpha radiation. This radiation has a short range with intense ionization hence thick tracks

(c)It is a semiconductor in which impurities have been added to change conductivity

(d) By connecting it in a forward biased mode

(ii)Across QS

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FORM I - PHYSICS SYLLABUS

Introduction to Physics (4 Lessons)
Measurements 1 (12 Lessons)
Force (16 Lessons)
Pressure (24 Lessons)
Particulate Nature of Matter (12 Lessons)
Thermal Expansion (12 Lessons)
Heat Transfer
Rectilinear Propagation of Light and Reflection at Plane Surface (16 Lessons)
Electrostatics (12 Lessons)
Cells and Simple Circuits (12 Lessons)

FORM II - PHYSICS SYLLABUS

Magnetism (12 Lessons)
Measurements II (16 Lessons)
Turning Effect of Force (10 Lessons)
Equilibrium Centre of Gravity (12 Lessons)
Reflection at Curved Surfaces (16 Lessons)
Magnetic Effect of Electric Current (18 Lessons)
Hooke's Law (8 Lessons)
Waves (14 Lessons)
Sound (12 Lessons)
Fluid Flow (14 Lessons)

FORM III - PHYSICS SYLLABUS

Linear Motion (20 Lessons)
Refraction of Light (20 Lessons)
Laws of Motion (15 Lessons)
Energy, Power and Machines (20 Lessons)
Current Electricity (20 Lessons)
Waves II(10 Lessons)
Electrostatics II (15 Lessons)
Heating Effect of Electric Current (10 Lessons)
Quantity of Heat (20 Lessons)
Gas Laws (15 Lessons)

FORM IV - PHYSICS SYLLABUS

Thin Lenses (20 Lessons)
Uniform Circular Motion (10 Lessons)
Floating and Sinking (15 Lessons)
Electromagnetic Spectrum (15 Lessons)
Electromagnetic Induction (20 Lessons)
Mains Electricity (10 Lessons)
Cathode Rays and Cathode Ray Tube (10 Lessons)
X-rays (8 Lessons)
Photoelectric Effect (15 Lessons)
Radioactivity (15 Lessons)
Electronics (10 Lessons)

K.C.S.E Physics Q & A - MODEL 2019PP2QN19

K.C.S.E Physics Q & A - MODEL 2019PP2QN19

K.C.S.E Physics Q & A - MODEL 2019PP2QN12

K.C.S.E Physics Q & A - MODEL 2019PP2QN12

Define radioactivity

Define radioactivity

K.C.S.E Physics Q & A - MODEL 2017PP2QN10

K.C.S.E Physics Q & A - MODEL 2017PP2QN10

Write an equation to show how an element ^A _Z X decay to element Y by emitting a beta particle.

K.C.S.E Physics Q & A - MODEL 2016PP2QN17

K.C.S.E Physics Q & A - MODEL 2016PP2QN17

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FORM I - PHYSICS SYLLABUS

FORM II - PHYSICS SYLLABUS

FORM III - PHYSICS SYLLABUS

FORM IV - PHYSICS SYLLABUS

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PRIMARY SCHOOL RESOURCES CBC

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K.C.S.E Physics Q & A - MODEL 2019PP2QN19

K.C.S.E Physics Q & A - MODEL 2019PP2QN19

K.C.S.E Physics Q & A - MODEL 2019PP2QN12

K.C.S.E Physics Q & A - MODEL 2019PP2QN12

Define radioactivity

Define radioactivity

K.C.S.E Physics Q & A - MODEL 2017PP2QN10

K.C.S.E Physics Q & A - MODEL 2017PP2QN10

Write an equation to show how an element A Z X decay to element Y by emitting a beta particle.

K.C.S.E Physics Q & A - MODEL 2016PP2QN17

K.C.S.E Physics Q & A - MODEL 2016PP2QN17

Categories

FORM I - PHYSICS SYLLABUS

FORM II - PHYSICS SYLLABUS

FORM III - PHYSICS SYLLABUS

FORM IV - PHYSICS SYLLABUS

Archives

M.A Nyamoti

HIGH SCHOOL RESOURCES

PRIMARY SCHOOL RESOURCES 8-4-4

PRIMARY SCHOOL RESOURCES CBC

COLLEGE RESOURCES

FREE NOVELS

Write an equation to show how an element ^A _Z X decay to element Y by emitting a beta particle.