Free KCSE Physics Topical Questions KNEC Standards

K.C.S.E Physics Q & A - MODEL 2019PP2QN09

31/7/2020

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K.C.S.E Physics Q & A - MODEL 2019PP2QN09

Figure 4 shows the input and output signals on a CRO screen when two diodes are used during a full wave rectification.

Explain how the two diodes rectify the input signal.

answers

During the first half cycle of the input signal, current flows in the first diode
During the second half cycle of the input signal, current flows in the second diode
When the current through the two diodes are combined a fully rectified wave signal is obtained as the output signal.

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K.C.S.E Physics Q & A - MODEL 2017PP2QN19

28/7/2020

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K.C.S.E Physics Q & A - MODEL 2017PP2QN19

(a) Figure 10 shows a block diagram of a cathode ray oscilloscope (CRO).

State the names of the parts labelled B₁ and B₂.
(ii) State and explain the function of the part marked A.
(b) Figure 11 shows a trace of a signal observed on the screen of a CRO. The time-base setting is 20 mscm^-2

Determine the frequency of the signal.
(c) Explain why tunsten is used as a target in an x-ray tube.

answers

a) (i) B1 — y deflecting plates
B2 — x deflecting plates
(ii) Grid; controls the intensity by controlling the number of electrons reaching the screen.
If made more negative less electrons pass through.

c) Tungsten has a high melting point.
It can with stand high temperatures.

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K.C.S.E Physics Q & A - MODEL 2015PP2QN12

24/7/2020

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K.C.S.E Physics Q & A - MODEL 2015PP2QN12

Figure 4 shows a cathode ray entering into a region between two charged plates.

Complete the diagram to show the path of the ray in the field.

answer

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K.C.S.E Physics Q & A - MODEL 2014PP2QN13

23/7/2020

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K.C.S.E Physics Q & A - MODEL 2014PP2QN13

The current of electrons hitting the screen of a cathode ray oscilloscope is 2.0 X 10^-4A
Determine the number of electrons that strike the screen each second. (take charge of an electron as 1.6 X 10 ^-19C).

answer

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K.C.S.E Physics Q & A - MODEL 2013PP2QN017

23/7/2020

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K.C.S.E Physics Q & A - MODEL 2013PP2QN017

(a) Figure 9 shows a cathode ray tube in which a beam of electrons is cast on the screen.

(i) state how the electrons are produced in the tube.
(ii) state how the electron beam is detected.
(iii) State the reason for having a variable potential difference (p.d.) at the:
(I) grid;
(II) anodes.
(b) Figure 10 shows the waveform of a signal applied at the y-plates of an oscilloscope whose time-base is switched to the scale of 2 milliseconds per centimeter.

Determine:
(i) the period of the signal;
(ii) the frequency of the signal.

ANSWERS

(a) (I) Thermionically by cathode
(ii) causing fluorescence on screen
(iii) (i) control brightness of fluorescence
(ii) to focus the electron beam

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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 2019PP2QN09

K.C.S.E Physics Q & A - MODEL 2019PP2QN09

K.C.S.E Physics Q & A - MODEL 2017PP2QN19

K.C.S.E Physics Q & A - MODEL 2017PP2QN19

State the names of the parts labelled B₁ and B₂.
(ii) State and explain the function of the part marked A.
(b) Figure 11 shows a trace of a signal observed on the screen of a CRO. The time-base setting is 20 mscm^-2

K.C.S.E Physics Q & A - MODEL 2015PP2QN12

K.C.S.E Physics Q & A - MODEL 2015PP2QN12

K.C.S.E Physics Q & A - MODEL 2014PP2QN13

K.C.S.E Physics Q & A - MODEL 2014PP2QN13

The current of electrons hitting the screen of a cathode ray oscilloscope is 2.0 X 10^-4A
Determine the number of electrons that strike the screen each second. (take charge of an electron as 1.6 X 10 ^-19C).

K.C.S.E Physics Q & A - MODEL 2013PP2QN017

K.C.S.E Physics Q & A - MODEL 2013PP2QN017

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K.C.S.E Physics Q & A - MODEL 2019PP2QN09

K.C.S.E Physics Q & A - MODEL 2019PP2QN09

K.C.S.E Physics Q & A - MODEL 2017PP2QN19

K.C.S.E Physics Q & A - MODEL 2017PP2QN19

State the names of the parts labelled B1 and B2. (ii) State and explain the function of the part marked A. (b) Figure 11 shows a trace of a signal observed on the screen of a CRO. The time-base setting is 20 mscm-2

K.C.S.E Physics Q & A - MODEL 2015PP2QN12

K.C.S.E Physics Q & A - MODEL 2015PP2QN12

K.C.S.E Physics Q & A - MODEL 2014PP2QN13

K.C.S.E Physics Q & A - MODEL 2014PP2QN13

The current of electrons hitting the screen of a cathode ray oscilloscope is 2.0 X 10-4A Determine the number of electrons that strike the screen each second. (take charge of an electron as 1.6 X 10 -19C).

K.C.S.E Physics Q & A - MODEL 2013PP2QN017

K.C.S.E Physics Q & A - MODEL 2013PP2QN017

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FORM I - PHYSICS SYLLABUS

FORM II - PHYSICS SYLLABUS

FORM III - PHYSICS SYLLABUS

FORM IV - PHYSICS SYLLABUS

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HIGH SCHOOL RESOURCES

PRIMARY SCHOOL RESOURCES 8-4-4

PRIMARY SCHOOL RESOURCES CBC

COLLEGE RESOURCES

FREE NOVELS

Send Us a Message

State the names of the parts labelled B₁ and B₂.
(ii) State and explain the function of the part marked A.
(b) Figure 11 shows a trace of a signal observed on the screen of a CRO. The time-base setting is 20 mscm^-2

The current of electrons hitting the screen of a cathode ray oscilloscope is 2.0 X 10^-4A
Determine the number of electrons that strike the screen each second. (take charge of an electron as 1.6 X 10 ^-19C).