Free KCSE Physics Topical Questions KNEC Standards - ATIKA SCHOOL

K.C.S.E Physics Q & A - MODEL 2005PP2QN07

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP2QN07

(a) What is meant by radioactivity
(b) With an aid of a labeled diagram explain the working of Geiger Muller tube as a detector of radiation
(c) In an experiment to determine the half of a certain radioactivity substance, the activity in disintegrations per minute was measured for sometime. Table 1 shows the results obtaine

On the grid plot a suitable graph and sue it to determine the half life t ½ of the substance
(d) At time t = 40 minutes, the activity of a sample of a certain radioactive isotope with a half life 12 minutes if found to be 480 disintegration per minute.
Determine the time which activity was 3840 disintegrations per minute

answers

K.C.S.E Physics Q & A - MODEL 2005PP2QN06

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP2QN06

(a) Define the term angular velocity
(b) A body moving with uniform angular velocity is found to have covered an angular distance of 170 radians in t seconds. Thirteen seconds later it is found to have covered a total angular distance of 300 radians. Determine t.
(c) Fig 8 shows a body of mass m attached to the centre of a rotating table with a string whose tension can be measured. (The device for measuring the tension is not shown in the figure)

The tension, T on the string was measured for various values of angular velocity, w. The distance r of the body from the centre was maintained at 30cm. Table 1 shows the results obtained.

(i) Plot the graph of T (y- axis against w²)
(ii) From the graph, determine the mass, m of the body given that
T = mw²–C
Where C is a constant
(iii) Determine the constant C and suggest what it represents in the set up.

answers

K.C.S.E Physics Q & A - MODEL 2005PP2QN05

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP2QN05

(a) State Hooke's law
(b) One of a piece of a rubber was fixed to a rigid support and the other end pulled with a force of varying magnitude. The graph in fig 6 shows the relationship between the force (N) and the extension (cm)

Using the graph, determine
(i) The stretching force at the elastic limit
(ii) The tensile stress in the rubber at an extension of 5 cm if the cross-section of the rubber is 0.25cm2
(iii) The tensile in the rubber at an extension of 5cm if the original length was 2 m
(c) In Fig 7. girders AB, BC, CD, ED, EB and BD were joined to make the rigid structure shown. The load W hangs from the structure as shown.

Which of the girders can be replaced with strings without affecting the structure?

answers

K.C.S.E Physics Q & A - MODEL 2005PP2QN04

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP2QN04

Explain how doping producers an n-type semi-conductor for a pure semi-conductor material.
b) Fig 5. Shows the circuit of a rectifier using four diodes D1, D2, D3 and d4.

(i) Explain how a rectified output is produced from the set – up when an a.c input is connected across AB
(ii) On the axis provided sketch the graph of output voltage against time for rectifier
(iii) A capacitor is now connected across XY. Explain the effect of the capacity on the output.
(c) A transistor in a common-emitter amplifier has life = 120. A signal in the input causes the base corresponding change in the output voltage if the load resistance is 100n.

answers

K.C.S.E Physics Q & A - MODEL 2005PP2QN03

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP2QN03

3 When the switch is closed determine the:
(i) Ammeter reading
(ii) Charge on each conductor

answers

K.C.S.E Physics Q & A - MODEL 2005PP2QN02

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP2QN02

a) Fig 2. Shows a wheel and axle being used to raise a load W by applying an effort F The radius of the large wheel is R and of the small wheel r as shown.

(i) Shows that the velocity ratio (V.R) of this machine is given by R/r
(ii) Given that r= 5cm, r=8cm, determine effort required to raise a load of 20N if the efficiency of the machine is 80%
(iii) It is observed that the efficiency of the machine increases when it is used to lift large loads. Give a reason for this.

answers

K.C.S.E Physics Q & A - MODEL 2005PP2QN01

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP2QN01

a) Describe with aid of a labeled diagram an experiment to determine the focal length of the lens when provided with the following; an illuminated object, convex lens, a lens, a lens holder, a plane mirror and a metre rule.
b) A small vertical object is placed 28cm in front of a convex lens of focal length 12cm. On the grid provided, draw a ray diagram to locate the image. The lens position is shown.
(Use a scale; 1cm rep re 4cm)
Determine the image distance.
c) Fig 1 shows a human eye with a certain defect

(i) Name the defect
(ii) On the same diagram, sketch the appropriate lens to correct the defect and sketch rays to show the effect of the lens.

answers

K.C.S.E Physics Q & A - MODEL 2005PP1QN38

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN38

Fig 18 shows two spherical materials one an insulation conductor, the other a conductor, Negative charge are introduced at point A in each case.

One the same figure indicate the final position of the charges. Explain your answer.

ANSWERS

K.C.S.E Physics Q & A - MODEL 2005PP1QN37

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN37

In the set up Fig 17 the metal rod is made up of steel and iron pieces joined end. Your are provided with two iron nails

Explain how you would use two nails provided to determine which side is iro

ANSWERS

When the switch is closed and nails attracted.
When the switch is opened, the nail on the iron end drops first.

K.C.S.E Physics Q & A - MODEL 2005PP1QN36

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN36

The following represents a nuclear reaction involving the nuclide polonium P

Identify m, n and X
m
n
X

ANSWERS

Draw appropriate symbols the circuit diagram of a junction diode in reverse bias.

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN35

Draw appropriate symbols the circuit diagram of a junction diode in reverse bias.

ANSWER

Explain why a drop of methylated spirit on the back of the hand feels colder than a drop of water at the same temperature.

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN34

Explain why a drop of methylated spirit on the back of the hand feels colder than a drop of water at the same temperature.

ANSWER

Methylated spirit evaporates faster/highly volatile than water taking latent heat away faster from the hand.

The target of X-ray tube s made of melting point. Give a reason for this

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN33

The target of X-ray tube s made of melting point. Give a reason for this

ANSWER

To withstand the high temperature (immerse heat) prevent the target from melting due to high temperature or immense heat.

K.C.S.E Physics Q & A - MODEL 2005PP1QN32

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN32

Fig 16 shows wave fronts in a ripple tank approaching a shallow region in the tank

Complete the diagram to show the wave front as they pass over the shallow region and after leaving the regions

ANSWER

Explain how an “excited‟ hydrogen atom is able to emit radiations of different wavelengths.

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN31

Explain how an “excited" hydrogen atom is able to emit radiations of different wavelengths.

ANSWERS

In excited state the electron is in a higher (outer) energy level. As it falls back it releases energy and may fall in steps releasing different energies (radiations) (proton) packets energy.

K.C.S.E Physics Q & A - MODEL 2005PP1QN30

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN30

An illuminated vertical object is initially placed on the principal axis of a converging lens and 32cm from it. The focal length of the lens 15cm. The object is new placed at a point 12cm from the lens and on the same side. State two changes other than magnification than magnification that that are observed on the image formed due to this change.

ANSWER

Image changes from real to virtual
Image changes from inverted to upright
Image changes from behind lens to the same side as object.

K.C.S.E Physics Q & A - MODEL 2005PP1QN29

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN29

A car of mass 800kg moves on a circular track of radius 20m. The force of friction between the tyres and the tarmac is 4800N Determine the maximum speed at which the car can be driven on the track without skidding.

ANSWER

K.C.S.E Physics Q & A - MODEL 2005PP1QN28

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN28

Fig 15 shows an arrow which indicates the direction of travel of a wave in a medium. P is a particle of the medium that is in path of the wave.

In the space provided sketch diagram to show how the particles P moves when the wave is
(i) A transverse wave
(ii) A longitudinal wave.

ANSWER

K.C.S.E Physics Q & A - MODEL 2005PP1QN27

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN27

The melting point of oxygen is given as -281.3⁰C. Covert this temperature to Kelvin (K)

ANSWER

273+ -281.3 = 8.3K

State Bernoulli's principle.

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN26

State Bernoulli's principle.

ANSWERS

At steady rate, the sum of pressure, the potential energy per unit volume and kinetic energy per Unit volume in fluid in a constant.
Provided a finish is non-viscous, incompressible and its flow streamline and increase in its velocity produces a corresponding decrease in pressure
When the speed of a fluid increases, the pressure in the fluid decreases and vice versa.

K.C.S.E Physics Q & A - MODEL 2005PP1QN25

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN25

Fig 14 shows the velocity- time graph for a small metal sphere falling through a viscous fluid.

On the axes provided sketch the graph of momentum against time for the same mass.

ANSWER

K.C.S.E Physics Q & A - MODEL 2005PP1QN23&24

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN23&24

Fig 13 shows rays of light AO,BO, and CO incident on a glass-air interface. OA" OB" and OC" are the corresponding emergent rays. Study and answer questions 23 and 24.

Determine the critical angles of the glass material
Determine the refractive of index of the glass material.

ANSWERS

K.C.S.E Physics Q & A - MODEL 2005PP1QN22

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN22

Fig. 12 shows a vertical object, O, placed in front of a convex mirror.

On the same diagram draw the appropriate rays and locate the image formed

ANSWER

K.C.S.E Physics Q & A - MODEL 2005PP1QN20&21

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN20&21

Fig 11 shows the variation of temperature, with time t, when an immersion heater is used to heat a certain liquid. Study the figure and answer questions 20 and 21.

State the reason for the shape of graph in the section labeled BC
Sketch on the same axes the graph for another liquid of the same mass but higher specific heat capacity when heated from the same temperature.

ANSWERS

A hair drier is rated 2500W, 240V. Determine its resistance.

13/7/2020

K.C.S.E Physics Q & A - MODEL 2005PP1QN19

A hair drier is rated 2500W, 240V. Determine its resistance.

answer

CATEGORIES

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Topics

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)

TOPICS

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)

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