Free KCSE Physics Topical Questions KNEC Standards

K.C.S.E Physics Q & A - MODEL 2019PP2QN14

31/7/2020

K.C.S.E Physics Q & A - MODEL 2019PP2QN14

Figure 6 shows radiation from the sun passing through glass in a greenhouse onto the floor. The floor then emits radiation

State the name of the radiation emitted by the floor.

answer

Infrared

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K.C.S.E Physics Q & A - MODEL 2018PP2QN16

29/7/2020

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K.C.S.E Physics Q & A - MODEL 2018PP2QN16

(a) State the meaning of the following terms:
(i) Photoelectric effect
(ii) Threshold frequency
(b) Figure 5 shows some light incident on the cathode of a photocell. The photocell is connected in series with a battery, a variable resistor and a microammete

(î) Explain how the microammeter reading is affected when the intensity of the incident light is increased.
(ii) State the reason why the tube is evacuated
(c) Figure 6 shows a graph of maximum kinetic energy (KE max) of photoelectrons against the frequency of the incident radiation.

From the graph, determine:
(i) Plank’s constant h,
(ii)the threshold wavelength given that the speed of light C is 3.0 x 10⁸ms^-1

answers

(a)(i) The emission of electrons from a metal surface when light/electromagnetic radiations shine on it.
(ii) The minimum frequency of radiation required to eject electrons from a metal surface.
(b)(i) Increased intensity increases the number of electrons emitted hence a higher current reading on the microammeter.
(ii) To minimize collisions between electrons and air molecules which would cause loss of energy.

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K.C.S.E Physics Q & A - MODEL 2017PP2QN16

28/7/2020

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K.C.S.E Physics Q & A - MODEL 2017PP2QN16

(a) Figure 7 shows a set up that may be used to observe photoelectric effect. A radiation is incident on the cathode. it is observed that the microammeter registers a current.

(i) Explain how the current is produced.
(ii) State with a reason what must be done for a higher current to be registered.
(iii) It was observed that for a certain incident radiation, no current was registered.
Explain this observation.
(b)A monochromatic light of wavelength 4.50 X 10^-7 m is incident on a metal surface of threshold frequency 5.5 X 10¹⁴ Hz. (Speed of light c is 3.0 X 10⁸ms and planks constant h is 6.63 X 10^-34Js).
Determine
(i) the work function of the metal surface,
(ii) average kinetic energy of the emittal photoelectrons.

answers

a)i. Radiations cause photo electrons to be ejected from the metal surface (cathode), the electrons are attracted by the anode hence current flows.
ii)Source is made moved closer! increase anode voltage/accelerating voltage.
iii. The frequency of the incident radiation is below the thrsio1d frequency of the surface hence no emission can take place.

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K.C.S.E Physics Q & A - MODEL 2015PP2QN14

24/7/2020

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K.C.S.E Physics Q & A - MODEL 2015PP2QN14

(a) State two factors that affect photoelectric emission.
(b) Light of wavelength 4.3 x 10^-7m is incident on two different metal surfaces, nickel and potassium. (Take speed of light as 3.0 x 10⁸ ms^-1 and planks constant h as 6.63 x 10^-34Js).

(i) Determine the energy of the incident radiation.
(ii) If the work function of nickel is 8.0 x 10^-19J and that of potassium is 3.68 x 10^-19J, state with a reason from which of the two metals the given light will eject electrons.
(iii) Determine the velocity of the emitted electrons from the metal surface in b(ii).
(Take the mass of an electron as 9.1 x 10^-31 kg).

answers

(a) Energy of incident radiation
Work function of the metal
Intensity of the radiation

(ii) Potassium
The work function of potassium is less than the energy of the incident radiation

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State one application of thermionic emission.

24/7/2020

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K.C.S.E Physics Q & A - MODEL 2015PP2QN11

State one application of thermionic emission.

answer

.Production of cathode rays / x-rays.

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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 2019PP2QN14

K.C.S.E Physics Q & A - MODEL 2019PP2QN14

K.C.S.E Physics Q & A - MODEL 2018PP2QN16

K.C.S.E Physics Q & A - MODEL 2018PP2QN16

From the graph, determine:
(i) Plank’s constant h,
(ii)the threshold wavelength given that the speed of light C is 3.0 x 10⁸ms^-1

K.C.S.E Physics Q & A - MODEL 2017PP2QN16

K.C.S.E Physics Q & A - MODEL 2017PP2QN16

K.C.S.E Physics Q & A - MODEL 2015PP2QN14

K.C.S.E Physics Q & A - MODEL 2015PP2QN14

(a) State two factors that affect photoelectric emission.
(b) Light of wavelength 4.3 x 10^-7m is incident on two different metal surfaces, nickel and potassium. (Take speed of light as 3.0 x 10⁸ ms^-1 and planks constant h as 6.63 x 10^-34Js).

State one application of thermionic emission.

State one application of thermionic emission.

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FORM I - PHYSICS SYLLABUS

FORM II - PHYSICS SYLLABUS

FORM III - PHYSICS SYLLABUS

FORM IV - PHYSICS SYLLABUS

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K.C.S.E Physics Q & A - MODEL 2019PP2QN14

K.C.S.E Physics Q & A - MODEL 2019PP2QN14

K.C.S.E Physics Q & A - MODEL 2018PP2QN16

K.C.S.E Physics Q & A - MODEL 2018PP2QN16

From the graph, determine: (i) Plank’s constant h, (ii)the threshold wavelength given that the speed of light C is 3.0 x 108ms-1

K.C.S.E Physics Q & A - MODEL 2017PP2QN16

K.C.S.E Physics Q & A - MODEL 2017PP2QN16

K.C.S.E Physics Q & A - MODEL 2015PP2QN14

K.C.S.E Physics Q & A - MODEL 2015PP2QN14

(a) State two factors that affect photoelectric emission. (b) Light of wavelength 4.3 x 10-7m is incident on two different metal surfaces, nickel and potassium. (Take speed of light as 3.0 x 108 ms-1 and planks constant h as 6.63 x 10-34Js).

State one application of thermionic emission.

State one application of thermionic emission.

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

From the graph, determine:
(i) Plank’s constant h,
(ii)the threshold wavelength given that the speed of light C is 3.0 x 10⁸ms^-1

(a) State two factors that affect photoelectric emission.
(b) Light of wavelength 4.3 x 10^-7m is incident on two different metal surfaces, nickel and potassium. (Take speed of light as 3.0 x 10⁸ ms^-1 and planks constant h as 6.63 x 10^-34Js).