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PHYSICS KCSE PAST PAPER QUESTIONS MARKING SCHEMES FROM 1995-2014

K.C.S.E 1995 PAPER 1 MARKING SCHEME

  1. Micrometer screw gauge
  1. Effort would reduce
  2. Flow from a to B
  3. Pressure difference between liquids in A and B is P = egh where e is liquid, g = acceleration due to gravity and h is height

But force = P x cross section area of siphon, P = F/A

Thus F = egh A           Since e.g. A are constants

Fα h    

  1. No change in flow OR the flow will still continue
  2. Oil spread until it is one molecule thick or film taken as a perfect circle or oil drop has been taken  as perfect sphere/ cylinder/ uniform thickness
  3. The liquid expand uniformly, expansion  is measurable ( large enough), thermal conductivity
  4. Rectilinear propagation/ light travels  in a straight line
  5. Water/ or glass are poor conductor of heat
  6. Each material is brought in turn to touch the cap. The conductor will discharge the electroscope while  the insulator will not  ( accept bring near conductor gauge)
  7. Can be short – circuited without  being destroyed
    1. Longer life/ electrolyte never need attention
    1. Can stay discharged without being destroyed
    1. Can be charged with  large currents faster charging
    1. More rugged/ not damaged by rough condition of use/ robus
    1. Delivers large current, light
  8. Surface tension / adhesive forces supports water column or more capillarity in tube 2 than tube 1
    1. Surface tension is the same in both tubes and equal to the  weight  of water column supported
    1. Narrow tube has longer column to equate weight to wider tube
    1. Volume of water  in the tubes  is same hence narrower tube higher column
  1. – Length of conductor in the field

– Angle between conductor and fields

  1. All ferromagnetic  materials are attracted by magnets or any magnetic materials is attracted
  2. – increasing the tension

– Reducing the length 

  1. At equilibrium sum of clockwise moment = sum of anti – clockwise moments

Clockwise moments = P  x    X = QY

                                     Px = Qy

  1. h glass = V air / V glass                                  1.5 = 3 x 108 Ö g

Vg = 3 x 108 / 1.5                                = 2 x 108 ms-1

  1. V = f l sine V is constant reducing f to 1/3 Þ          l increases 3 fold
  2. While light is composed of seven colour different/ many colour. For each colour glass had different value of refractive index/ different velocities of different l. So each colour is   deviated differently causing dispersion
  1. A body at rest or in state of uniform motion tends to stay in that state unless an unbalanced force acts on it.
  1. Heat capacity  is quantity  of heat required to raise the temperature  of the  body by 1 k or 1 0C while, specific heat capacity is quantity of heat required to raise temperature of unit  mass of body by 1 k/ 10 C.
  1. (If x ≠z but both above y give  1 mk. Accept difference of 1.0 mark)
PHY 011

            hX = hZ > hY

  1. – Reducing                                          – Increasing
  1. Polarization
Type of radiation Detector Uses
Ultra violet Photographic paper fluorescence material Cause ionization kills bacteria OR operating photosular cells photography
Infrared Phototransistor blackened thermometer Warmth sensation
Radio waves Radio receiver  or TV  receiver Communication
  1. E2 = E1 + h f  i             or E2 – E1= h = c/l

h= plank constant

c- Velocity of light

l- Wave length of light

  1. – Lead                         – Very dense/ has high atomatic mass
  2. Extrapolation on graph  ( line to touch frequency)

Reading on graph to (4.0 + – 0.2) x 1014Hz

  1. Lines parallel to the one shown but cutting  of axis further in
  2. Quality / Timbre
  3. X = 14
  4. The point where the weight of the body acts
  5. Temperature of source be the same

– Length of rods be the same / wax

– Amount of wax (detector) be the same

PHY 013

K.C.S.E 1995 PHYSICS PAPER 232/2 MARKING SCHEMES

PHY 020

1. (a)

(b) Constant Vel0                                Uniform vet                – zero accln

(c)        Ö4.5 = 118 – 50 = 15m/s         15.5 + -1.5 ( 14-17)

                        6.5-2

            Ö 6.5 = 112 – 70 = 6 m/s         (4=6)

                           7

            Average accln = ∆v = v – 11  = ( 6-15)

                                        t             t           2

                                                                                                = – 4.5 m/s2     

2.         l =   7   +  l  +  l

            RC   R1      R2   R3

            =          1    +   1   +   1

                        6    +   3         6

            = 1

                6

            RC = 6 = 1.5 W

                    4

            (b) Total resistance = 1.5 + 2.5 = 4 W

                        E = 1(YFR) Or l = V

                                                       R

                        2 = Ll

                        Current through xy l = 0.5 A

                        P.d across yz               = 0.5 x 1.5 V

                        s= current through 3 W = 0.5 x 1.5 = 0.25 A

                                                                        3

            (c) R = /L        A

                        I           = RA               = 6 x 5.0 x 10-6  Wm2

                                         L                        1.0                 m

                        = 3.0 x 10-5W m

3.         (a)

PHY 021
PHY 022

            (ii) Magnification = V  Isign   = 1.1    OR      1.75

                                             u Osign       1.6               2.5                   = 0.7 ± 0.05

  • l = l + l                         l = 10

f    u    v                       u    60

 l  = l   +  l                    u = 6cm

10   u      v      

l  = l  +   l                     Objects is 6 cm from the lens

U  10    15

4 (a) Lens symbol object between f & F 2 appropriate rays position of image

PHY 023

            Image correctly drawn

PHY 024

            The diagram in figure 3 shows a certain eye defect

            (b) (i) Name of defect  is long sightedness

                        (Refer to the diagram in the figure 3 above)

(c) (i) For water not to pour weight of  the water must be less centrifugal force OR for water to pour out MV2 > mg

                                                 r

            (ii) Frictional force F   = Centripetal force

                                                            MV2                = 1200 x (25)2

                                                              R                        150

                                                                        = 5.0 x 103N

5. (a) (i) The magnitude of the induced e.m.f is directly proportional to the rate at which the conductor cuts the magnetic field lines

The induced current flows in such a direction as to oppose the changes producing it.

(ii) Plugging a magnetic into a coil

  • in speed its g twins as straight of magnetic field
  • Results in an increased in the induced e.m.f

(b) (i) Energy is neither created nor destroyed

            Make power constant

            VU = Joules ( ½ )        current = charge ( ½ )

                        Count                               time

                        P = IV

            For large V, 1 must lower for power input to be equal to power output

(ii)        Vs – Vp                                  OR Vs –   Na

             Ns     Vp                                        Vp    NP

            Ns = Vs x Np              =          9 x 480

                        Vp                                  240                           Ns = 18

SECTION II

6. (a ) Progressive wave- Wave profile moves along with the speed of the wave

            Stationary wave – wave profile appears static

Progressive wave – Phase of points adjacent to each other is different

Stationary wave – All points between successive node vibrate in phase

Progressive wave – Energy translation in the direction of the wave travels

Stationary wave- No translation of energy but energy associated in the wave

(b) (i)   A glass slide i.e. blackened with soot or paint lines are drawn close together using

a razor blade or  pin.

PHY 025

(ii)        Path differences equals to an odd number of half wavelengths or completely out of phase ( 1800)

(iii)       Photometer / photocell or thermometer with a bulb

7.         (a) Common or sillen ( semiconductor) is doped with impurity atoms which trivalent ( e.g boron or indium) intensity in currency on pole group 4 doped with trivalent

            (b) p-n-p emitter and carries made of p type material are of n- type material for charge carries holes

  • n – p – n – emitter and collector made of n- type material are made of p- type (  or charge carries electrons)

(c) At the middle of the reaction of a curve a tangent is drawn change on output (∆V0) is determined and a corresponding change input ( ∆V1) also attained change amplification.

PHY 026

(d) (i)

(ii) i2 = lC r lB

(e) Base – emitter – forward biased                Base collector – reversed biased

PHYSICS PAPER 231/1A 1996 MARKING SCHEMES

  • Correct full marks to be given
  • Wrong units no marks  given
  • Wrong substitution no mark
  • No units full  mark
  1. 15.00 + 0.30 = 15. 30 mm; or 1.53 / 1.53 x 102m
  2. Frequency: OR wavelength or energy
  3. Length of container/ height

Width of the base/ base area/ diameter/ radius of the base/ thickness

  1. hp p1 g = h2 p2g            Same as h1 p1= h2 p2

h1 = h2 p2g                   = 8 x 18

            pg                              08

                        = 18cm;

  1. (i) Rubber is elastic and when a nail pushed through it stretches and grips the nail firmly without allowing air leakage

(ii) Valve effect pressure from inside causes tyre rubber to press firmly on the nail

  1. Concrete mixture and steel have approximately the same linear expansively. The expand/ contract at the same rate;
  2. Radiation is at the electromagnetic waves Φ infrared while conduction involves particles, which move at lower  speed
  3. There are three different sources  of light  of the different intensities; brighten/ dimmed / different direction/ amount quality. Similar sources/ at  different distances from the object
  4. like charges repel unlike  charges attract
  5. Mass per unit length

Or (linear density/ thickness/ cross – sectional area/ diameter, radius

  1. Adhesion

Cohesion/ surface tension

  1. As the thermistor is heated its resistance reduces/ conductivity  increases hence drawing more current through it;  hence  less current flowing through B;
  2. (i) (ii)
  1. T< F or F> T

Moments of T and F about are equal; but the perpendicular distance from O to T perpendicular distance from O to F/ Resultant moment are zero

  1. Turn anticlockwise  about O, OR Oscillate about O
  2.  
  1. The wavelength/ velocity of the water waves reduces; away from  the centre  because the pond  becomes shallower/ pond  deeper at centre
  2. Interferences  ( accept beat)
  3. Parallel resistor allow diversion of current; hence may not overheat; / current shared by parallel resistor
  4. Heat gained     5(80 – 40) = m(40-15) Heat gained MCD θ ( 80- 40)

5(40) = 25m                                        Heat post MCD θ =m (40 – 15) MC 40 – 15

                                                                        5(80-40) = 25 m

                                                                        25m = 200 = m = 8 kg

  1. Equal qualities of heated supplied;

MCWθW = MCPθP                                MCW (Qw –Q) = MCP (Qp – Q)

Since θP > θW                        or                     MCw > θ0 = MCP >QP

CW > θPCp

  1. Magnified, enlarged upright, virtual , image behind the mirror, negative  distance
  2. Apparent depth = Real Depth                                                12m = 0.9 m

Refractive indese of water      1.3

  1. Pressure is inversely proportional to the speed OR speed increases as pressure distance
  2. Maintaining a stable voltage during make and break/ storing charge during make and break and stops arcing sparking
  3. High temperature causes high – pressure build up in the cylinder, which causes the explosion; OR increases  of KE of gas molecules which result to pressure, build up causing an explosion                                                                   ( 2 mks)
  4. A Polaroid absorbs/ cuts off light waves in all planes except in a particular plane of propagation                                                                                        ( 1mk)
  5. A hears a constant frequency produced by the  siren/ same roundness/ pitch B hears a frequency that increases as the vehicle approaches/ sound of  increasing loudness/ higher sound                                                                             ( 2 mk)
  6. Solid copper is denser than water hence the solid sphere sinks; weight is greater than upthrust. Hollow sphere experiences an upthrust equal to its weight  so it will float/ density of hollow sphere  is less than  that of water               ( 2 mks)
  7. The weight of the  door and the force are  perpendicular to one  another     ( 1 mk)
  8. Eddy current                                                                                       ( 1 mk)
  9. Low negative voltage is applied on control grid, which control the number of electrons reaching the screen                                                                                    ( 1 mk)
  10. Low speed  / high charge / more massive/ size is large/ bigger`          ( 1 mk)
  11. n.p.n
  12. Limit the current through the base controls the current/ protect transistor from high current or voltage/ regulate reduce voltage.
  13. Diode  is forward biased; Base currents flows; hence  collector current flows and lights the bulb/ current amplification                                                   ( 3 mks)

air molecule are in constant random motion; smoke particles collide  with these air molecules hence their random motion

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