Free KCSE Physics Topical Questions KNEC Standards

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

28/7/2020

0 Comments

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.

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN18

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN18

(a) State two factors that affect the capacitance of a parallel plate capacitor.
(b) Figure 9 shows an electric circuit in which three capacitors are connected across a power supply.

Determine the;
(i) total capacitance,
(ii) quantity of charge stored on the 8uF capacitor.

answers

(a) — Area of overlap of the plates
— Distance between the plates.
— Type of dielectric.

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN17

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN17

(a) Figure 8 shows a conductor AB connected to a galvanometer and placed between two permanent magnets.

(i) Conductor AB is moved perpendicular to the magnetic field.
State and explain the observation made on the galvanometer.
(ii) State the effect of moving the conductor faster.
(b) A transformer is used to step down 240V to 12 V for use in an electric appliance operating at 0.5 A. If the primary coil has 600 turns, determine the;
(i) number of turns ¡n the secondary coil,
(ii) current in the primary coil.

answers

a) i. A momentary deflection is observed, Conductor cuts the field.
An emf is induced in AB Causing current in the circuit
ii. A bigger deflection is observed! higher current

0 Comments

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

28/7/2020

0 Comments

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.

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN15

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN15

(a) Figure 5 shows the interface between glass and air.

Draw on the figure a ray diagram to illustrate the critical angle.
(b) Figure 6 shows a ray of light incident at right angles to face AB of a right angled glass prism of refractive index 1.62.

(i) Determine the critical angle of the material.
(ii) Complete the ray diagram to show the path of light until it leaves the prism.
(c)State any two applications of prisms.

answers

(c)- Dispersion of white light
- In periscopes
- In Binoculars
- In telescopes

0 Comments

State how heating is achieved in a resistance wire.

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN14

State how heating is achieved in a resistance wire.

answer

.Conversion on the Kinetic energy of the electrons into heat energy/Conversion of electrical energy to heat

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN13

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN13

Figure 4 shows three resistors connected in series.

Using Ohm’s law, show that the effective resistance is given by the expression:
RT=RI+R2+R3

answer

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN12

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN12

Figure 3 shows a transverse wave.

Determine the frequency of the wave.

answer

0 Comments

Explain what is observed when an uncharged sphere is brought close to a positively charged electroscope.

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN11

Explain what is observed when an uncharged sphere is brought close to a positively charged electroscope.

answer

The leaf falls
Charge is induced on the sphere causing repulsion of electrons to the leaf hence leaf falls.

0 Comments

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

28/7/2020

0 Comments

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

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN09

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN09

Figure 2 shows a virtual image I formed by a convex lens.

Draw a ray diagram to locate the object.

answer

0 Comments

Draw a circuit diagram to show a p-n junction diode in the forward biased mode.

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN08

Draw a circuit diagram to show a p-n junction diode in the forward biased mode.

answer

0 Comments

Explain how the greenhouse gets warm.

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN07

Explain how the greenhouse gets warm.

answer

The light passes through the walls and gets absorbed by the soil, emitting energy of longer wavelengths which cannot penetrate the walls hence get trapped within the green house causing heating.

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN06

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN06

Figure 1 shows an insulated wire wound on a U-shaped iron core connected to a battery.

Determine the polarity of A.

answer

A — South pole

0 Comments

State two advantages of using convex mirrors to monitor movements in a large supermarket.

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN05

State two advantages of using convex mirrors to monitor movements in a large supermarket.

answer

Have a wide/wider field of view
Form upright images.

0 Comments

State what is meant by polarisation in simple cells.

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN04

State what is meant by polarisation in simple cells.

answer

Polarization is the formation of hydrogen gas at the positive terminal of the cell.

0 Comments

State one use of echoes.

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN03

State one use of echoes.

answer

Measuring distances speed of sound.

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN02

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN02

In a laboratory there are four metals — tin, nickel, copper and cobalt. Of these metals, name the metals that are;
(a) magnetic.
(b) non-magnetic.

answers

Magnetic — Nickel, cobalt
Non-magnetic — Tin, copper

0 Comments

State any two uses of microwaves.

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP2QN01

.State any two uses of microwaves.

answers

Cooking/warming/heating
Communication / Radar/ measure distances

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP1QN18

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP1QN18

(a) Figure 8 shows part of a hydraulic brake system.

Describe how the systems works.
(b) State three conditions necessary for a driver to negotiate a bend on a flat level road at a relatively high speed.
(c) Figure 9 shows two identical cans U and V each with a small opening at the top.
Different amounts of water were put into the cans and heated until the water started to boil.

Explain what will be observed when both cans are then suddenly dipped into a cold water bath.

answers

(a) (i) The driver applies a force on the pedal.
This force transmits pressure the master cylinder fluid.
Equal pressure is transmitted to the wheel cylinder causing the pistons of the wheel cylinder to push brake shoe hence
Pressing the brake pads that in turn press the wheel reducing its rotation.
When the applied force is removed, the return spring pulls back the shoe and pistons to the original position.
(b) Higher friction (wider tyres, rougher road)
Lower radius
Higher mass
(c) U is observed to crush.
It has more steam which when cooled creates a greater
vacuum hence pressure causes collapsing.

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP1QN17

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP1QN17

(a) State the law of flotation.
(b) Figure 6 shows two solids W and X made of the same material and immersed in water.

(i) State with a reason which one of the containers experiences a greater upthrust.
(ii) Solid W weighs 12 N in air, 2 N ¡n water and 4 N in another liquid. Determine the density of the other liquid.
(c) Figure 7 shows two identical wooden blocks each of mass 0.2 kg suspended in water by two strings M and N.

Given that the upthrust on each block is 3.2 N, determine the tension in string;
(i) M,
(ii) N.
(d) State any one application of hydrometers.

answers

(a) A floating body displaces its own weight of the fluid in which it floats.

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP1QN16

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP1QN16

(a) In an experiment to determine the size of an oil molecule, oil is placed on the surface of water after sprinkling lycopodium powder on it.
(i) State two reasons why oil is used.
(ii) State the function of the lycopodium powder.
(iii) State any two assumptions that are made in this experiment.
(iv) Explain why the oil spreads on the surface of water.

(b) The following data was obtained from an experiment to determine the size of a palm oil molecule.
— Volume of 100 drops of palm oil = 15.0mm³
— Area of a patch from one drop of oil = 8.0 X 10⁴ mm²
Determine the size of a palm oil molecule.

answers

(a) (i) Oil doesn’t mix with water.
Oil is less dense hence floats on the water surface.
(ii) To show boundary of the oil patch clearly, for measurements to be taken.
(iii) The oil drops is a perfect sphere.
The patch is monolayer.
The patch is a perfect circIe
Molecular diameter is uniform.
(iv) The oil breaks the surface tension V making the patch to form a perfect circle.

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP1QN15

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP1QN15

(a) A student was provided with several identical masses, a metre rule, a spring and a stand,
boss and clamp. Outline five steps that the student should follow in order to verify Hooke’s law.
(b) Figure 4 shows a graph that was drawn from the results obtained in an experiment to study the extension of a spring.

From the graph determine;
(i) The spring constant K,
(ii) The load that causes an extension of 3 X 10^-2 m.
(c) Three identical springs of spring constant 100 Nm^-1 are arranged as shown in Figure 5 to support a 5 N load.

Determine the total extension in the arrangement.

answers

(a) Hung the spring on the stand and note the position of the pointer using the metre rule.
Suspend a mass o the spring and note the new position of the pointer.
Increase the load in steps and record the position of the pointer for each load.
Draw a table of weight against extension.
Plot a graph of force against extension

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP1QN14

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP1QN14

(a) A tape attached to an accelerating trolley passes through a ticker timer that makes dots on it at a frequency of 50Hz. The ticker timer makes 10 dots on a 10cm long tape such
that; the distance a between the first two dots is 0.5 cm and the distance b between the last two dots is 1.5cm.

(i) Determine the velocity of the trolley at:
(I) distance a,
(II) distance b.
(ii) Determine the acceleration of the trolley.
(b) State with a reason what would be observed on the spacing between the dots on the tape when the trolley is made to move on a horizontal surface.

ANSWERS

(b) The spacing reduces with time.
The trolley decelerates with time on a horizontal surface.

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP1QN13

28/7/2020

0 Comments

K.C.S.E Physics Q & A - MODEL 2017PP1QN13

Figure 3 shows two possible designs of a three legged stool.

State a reason why B is more stable than A.

answer

0 Comments

<<Previous

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 2017PP2QN18

K.C.S.E Physics Q & A - MODEL 2017PP2QN17

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

K.C.S.E Physics Q & A - MODEL 2017PP2QN15

State how heating is achieved in a resistance wire.

K.C.S.E Physics Q & A - MODEL 2017PP2QN13

K.C.S.E Physics Q & A - MODEL 2017PP2QN12

Explain what is observed when an uncharged sphere is brought close to a positively charged electroscope.

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 2017PP2QN09

Draw a circuit diagram to show a p-n junction diode in the forward biased mode.

Explain how the greenhouse gets warm.

K.C.S.E Physics Q & A - MODEL 2017PP2QN06

State two advantages of using convex mirrors to monitor movements in a large supermarket.

State what is meant by polarisation in simple cells.

State one use of echoes.

K.C.S.E Physics Q & A - MODEL 2017PP2QN02

.State any two uses of microwaves.

K.C.S.E Physics Q & A - MODEL 2017PP1QN18

K.C.S.E Physics Q & A - MODEL 2017PP1QN17

K.C.S.E Physics Q & A - MODEL 2017PP1QN16

(b) The following data was obtained from an experiment to determine the size of a palm oil molecule. — Volume of 100 drops of palm oil = 15.0mm3 — Area of a patch from one drop of oil = 8.0 X 104 mm2 Determine the size of a palm oil molecule.

K.C.S.E Physics Q & A - MODEL 2017PP1QN15

From the graph determine; (i) The spring constant K, (ii) The load that causes an extension of 3 X 10-2 m. (c) Three identical springs of spring constant 100 Nm-1 are arranged as shown in Figure 5 to support a 5 N load.

K.C.S.E Physics Q & A - MODEL 2017PP1QN14

K.C.S.E Physics Q & A - MODEL 2017PP1QN13

Categories

FORM I - PHYSICS SYLLABUS

FORM II - PHYSICS SYLLABUS

FORM III - PHYSICS SYLLABUS

FORM IV - PHYSICS SYLLABUS

Archives

M.A Nyamoti

HIGH SCHOOL EXAMINATIONS

PRIMARY SCHOOL RESOURCES 8-4-4

PRIMARY SCHOOL RESOURCES CBC

COLLEGE RESOURCES

FREE NOVELS

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

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

(b) The following data was obtained from an experiment to determine the size of a palm oil molecule.
— Volume of 100 drops of palm oil = 15.0mm³
— Area of a patch from one drop of oil = 8.0 X 10⁴ mm²
Determine the size of a palm oil molecule.

From the graph determine;
(i) The spring constant K,
(ii) The load that causes an extension of 3 X 10^-2 m.
(c) Three identical springs of spring constant 100 Nm^-1 are arranged as shown in Figure 5 to support a 5 N load.