Free KCSE Physics Topical Questions KNEC Standards

K.C.S.E Physics Q & A - MODEL 2010PP2QN19

19/7/2020

K.C.S.E Physics Q & A - MODEL 2010PP2QN19

(a) State the property of radiation that determines the number of electrons emitted when a radiation falls on a metal surface.
(b) Figure 15 is a graph of the stopping potential Vs against frequency in an experiment on photoelectric effect.

(i) What is meant by stopping potential?
(ii) Given that the stopping potential Vs is related to the frequency by the equation

answers

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K.C.S.E Physics Q & A - MODEL 2010PP2QN18

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN18

Figure 14a, is a diagram of a cathode ray tube. M and N are parallel vertical plates.

(a) When switch S is open, a spot is seen at the centre of the screen as shown in figure 14(b).
(i) State what happens to the spot when S is closed.
(ii) State what would happen to the spot if the potential difference across MN is increased.
(iii) State what would be seen on the screen if the battery is replaced with an alternating emf of:
(I) a low frequency of about 1 Hz;
(II) a high frequency of about 50Hz.
(b) Explain the process by which electrons are produced at F.
(c) State with a reason how the brightness of the spot can be increased.
(d) The accelerating voltage of the tube is 1000V and the electron current in the beam is 1 .5mA. Determine the energy conveyed to the screen per second.

answers

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K.C.S.E Physics Q & A - MODEL 2010PP2QN17

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN17

(a) Figure 12, shows an electrical circuit including three switches, S1, S2, S3, and three identical lamps L1, L2, L3. A constant potential difference is applied across X and Y.

(î) Other than L1, state the lamp that will light when S1 and S2 are closed.
(ii) How does the brightness of L1 in (i) above compare with its brightness when all the switches are closed?
(iii) Explain the observation in part (ii) above.
(b) Figure 13, shows a cell in series with a 3ohms resistor and a switch. A high resistance voltmeter is connected across the cell.

The voltmeter reads 1.5V with the switch open and 1.2V with the switch closed.
(i) State the electromotive force of the cell.
(ii) Determine the current through the 3ohms resistor when the switch is closed.
(iii) Determine the internal resistance of the cell.
(c) (î) Another resistor R is connected in series with the 3ohms resistor so that a current of 0.15A flows when the switch is closed. Determine the resistance of R.

answers

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K.C.S.E Physics Q & A - MODEL 2010PP2QN16

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN16

(a) Figure 10, shows an object placed in front of a converging lens of focal length 50mm

(i) On the same figure, draw a ray diagram showing the location of the image.
(ii) Use the ray diagram to determine the:
(1) image distance;
(II) magnification.
(iii) State the adjustment that should be done to obtain a larger virtual image using the same lens.
(iv) State one application of the arrangement in figure 10.
(b) Figure 11, shows a pin 60 mm long placed along the principal axis of the lens used in part (a). The near end of the pin is 80 mm from the lens.

Determine the length of the image.

answers

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K.C.S.E Physics Q & A - MODEL 2010PP2QN15

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN15

(a) Figure 8, shows a circuit that may be used to charge a capacitor.

(i) state the observation on the milliameter when the circuit is switched on:
(ii) explain the observation in (î) above.
(b) The circuit in figure 8 is left on for some time. State the value of p.d. across:
(j) the resistor R;
(ii) the capacitor C;
(c) sketch the graph of potential difference (V) across R against time.
(d) Figure 9 shows three capacitors connected to a 10V battery.

Calculate:
(î) the combined capacitance of the three capacitors;
(ii) the charge on the 5.0 uF capacitor.

answers

(a) (1) High current which falls off to zero.
(ii) Current flows when the capacitor is charging. When fully charged current stop (no current) and p.d. is equal to charging voltage.

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K.C.S.E Physics Q & A - MODEL 2010PP2QN14

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN14

Figure 7, shows a block diagram of a p-n junction diode.

On the same diagram. show how a battery may be connected so that the diode is reverse biased.

answer

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K.C.S.E Physics Q & A - MODEL 2010PP2QN13

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN13

The wavelength of a radio wave is 1km. Determine its frequency.
(Take the speed of light as 3.0 x 108 ms^-1)

answer

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An x-ray tube produces soft x-rays. State the adjustment that may be made so that the tube produce s hard x-rays.

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN12

An x-ray tube produces soft x-rays. State the adjustment that may be made so that the tube produce s hard x-rays.

answer

Increase the acceleration voltage by setting a higher value.

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K.C.S.E Physics Q & A - MODEL 2010PP2QN11

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN11

Figure 6, shows a horizontal conductor in a magnetic field parallel to the plane of the paper.

State the direction in which the wire may be moved so that the induced current is in the direction shown by the arrow.

answer

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A current I flowing through a wire of resistance R was increased seven times. Determine the factor by which the rate of heat production was increased.

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN10

A current I flowing through a wire of resistance R was increased seven times. Determine the factor by which the rate of heat production was increased.

answer

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K.C.S.E Physics Q & A - MODEL 2010PP2QN09

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN09

The initial mass of a radioactive substance is 20g. The substance has a half-life of 5 years.
Determine the mass remaining after 20 years.

answer

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K.C.S.E Physics Q & A - MODEL 2010PP2QN08

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN08

A water wave of wavelength 18 mm is incident on a boundary of shallow water at right angles. If the wavelength in the shallow end is 14.4 mm, determine the refractive index of water for a wave moving from the deep to the shallow end.

answer

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K.C.S.E Physics Q & A - MODEL 2010PP2QN07

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN07

Figure 5, shows how the displacement of a point varies with time as a wave passes it.

On the same diagram, draw a wave which passes the point with half the amplitude and twice the frequency of the one shown.

answer

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Explain why electric power is transmitted over long distances at high voltages.

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN06

Explain why electric power is transmitted over long distances at high voltages.

answer

High voltages implies low current so reduces heat losses.

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K.C.S.E Physics Q & A - MODEL 2010PP2QN05

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN05

Figure 4, shows a bright electric lamp placed behind a screen which has a hole covered with a wire gauze. A concave mirror of focal length 25cm is placed in front of the screen. The position of the mirror is adjusted until a sharp image of the gauze is formed on the screen.

Determine the distance between the mirror and the screen.

answer

Distance = 2f 2 x 25=50 cm

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K.C.S.E Physics Q & A - MODEL 2010PP2QN04

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN04

A positively charged sphere is suspended by an insulating thread. A negatively charged conductor is suspended near it. The conductor is first attracted, after touching the sphere it is repelled. Explain this observation.

answer

Initially attracted because it is of opposite charge.
Then neutralized and charged positive and hence repel.

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K.C.S.E Physics Q & A - MODEL 2010PP2QN03

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN03

Figure 3, shows a diagram of a current-carrying wire wound on a U-shaped soft iron.

Draw the magnetic field pattern around P and Q.

answer

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K.C.S.E Physics Q & A - MODEL 2010PP2QN02

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN02

Figure 2(a), shows a magnetic compass placed under a horizontal wire XV

A large current is passed from X to Y. Draw the final position of the magnetic compass needle in figure 2b.

answer

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K.C.S.E Physics Q & A - MODEL 2010PP2QN01

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP2QN01

Figure 1, shows a ray of light incident on a plane mirror at O. The mirror is then rotated anticlockwise about O from position M1 to position M2 through an angle of 10°. The final reflected ray is OC

Determine the angle of deviation BOC

answer

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K.C.S.E Physics Q & A - MODEL 2010PP1QN19

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP1QN19

(a) Figure 9 shows a velocity-time graph for the motion of a certain bod

Describe the motion of the body in the region:
(i) OA;
(ii) AB;
(iii) BC.
(b) A car moving initially at 10 ms-1 decelerates at 2.5 m/s2.
(I) Determine:
(I) its velocity after 1 .5s;
(II) the distance travelled in 1.5s;
(III) the time taken for the car to stop.
(ii) Sketch the velocity-time graph for the motion of the car up to the time the car stopped.
(iii) From the graph, determine the distance the car travelled before stopping.

answers

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K.C.S.E Physics Q & A - MODEL 2010PP1QN18

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP1QN18

Figure 8 shows a stone of mass 4.0kg immersed in water and suspended from a spring balance with a string. The beaker was placed on a compression balance whose reading was 85N. The density of the stone was 3000kgm^-3 while the density of the liquid Was 800kgm^-3.
Determine the:

(a) volume of the liquid displaced;
(b) Upthrust on the stone;
(c) reading of the spring balance;
(d) reading of the compression balance when the stone was removed from the water

answers

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K.C.S.E Physics Q & A - MODEL 2010PP1QN17

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP1QN17

(a) Explain why it is advisable to use a pressure cooker for cooking at high altitudes.
(b) Water of mass 3.0kg initially at 20°C is heated in an electric kettle rated 3.0KW. The water is heated until it boils at 100°C. (Take specific heat capacity of water 4200J kg^-1K^-1, Heat capacity of the kettle = 450JK^-1 , Specific latent heat of vaporization of water = 2.3mJkg-1)

Determine:
(î) the heat absorbed by the water;
(ii) heat absorbed by the electric kettle;
(iii) the time taken for the water to boil;
(iv) how much longer it will take to boil away all the water

answers

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K.C.S.E Physics Q & A - MODEL 2010PP1QN16

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP1QN16

In an experiment to determine the density of sand using a density bottle, the following
measurements were recorded:
Mass of empty density bottle = 43 .2g
Mass of density bottle full of water = 66.4g
Mass of density bottle with some sand = 67.5g
Mass of density bottle with the sand filled up with water = 823g
Use the above data to determine the

(a) mass of water that completely tilled the bottle;
(b) volume of water that completely filled the bottle;
(c) volume of the density bottle;
(d) mass of sand;
(e) mass of water that filled the space above the sand;
(f) volume of the sand;
(g) density of the sand.

answers

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K.C.S.E Physics Q & A - MODEL 2010PP1QN15

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP1QN15

(a) A cyclist initially at rest moved down a hill without pedaling. He applied brakes and eventually stopped. State the energy changes as the cyclist moved down the hill.
(b) Figure 7 shows a mass of 30kg being pulled from point P to point Q, with a force of 200N parallel to an inclined plane. The distance between P and Q is 225m. In being moved from P to Q the mass is raised through a vertical height of 75m.
(i) Determine the work done:

I by the force;
II on the mass;
III to overcome friction.
(ii) Determine the efficiency of the inclined plane.
(c) Suggest one method of improving the efficiency of an inclined plane

answers

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K.C.S.E Physics Q & A - MODEL 2010PP1QN14

19/7/2020

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K.C.S.E Physics Q & A - MODEL 2010PP1QN14

Figure 6 shows an athlete lifting weights while standing with the feet apart

Explain why standing with the feet apart improves the athletes' stability.

answer

Increase the base area or lower the c.o.g.

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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 2010PP2QN19

K.C.S.E Physics Q & A - MODEL 2010PP2QN18

K.C.S.E Physics Q & A - MODEL 2010PP2QN17

K.C.S.E Physics Q & A - MODEL 2010PP2QN16

K.C.S.E Physics Q & A - MODEL 2010PP2QN15

K.C.S.E Physics Q & A - MODEL 2010PP2QN14

K.C.S.E Physics Q & A - MODEL 2010PP2QN13

The wavelength of a radio wave is 1km. Determine its frequency. (Take the speed of light as 3.0 x 108 ms-1)

An x-ray tube produces soft x-rays. State the adjustment that may be made so that the tube produce s hard x-rays.

K.C.S.E Physics Q & A - MODEL 2010PP2QN11

A current I flowing through a wire of resistance R was increased seven times. Determine the factor by which the rate of heat production was increased.

K.C.S.E Physics Q & A - MODEL 2010PP2QN09

K.C.S.E Physics Q & A - MODEL 2010PP2QN08

K.C.S.E Physics Q & A - MODEL 2010PP2QN07

Explain why electric power is transmitted over long distances at high voltages.

K.C.S.E Physics Q & A - MODEL 2010PP2QN05

K.C.S.E Physics Q & A - MODEL 2010PP2QN04

K.C.S.E Physics Q & A - MODEL 2010PP2QN03

K.C.S.E Physics Q & A - MODEL 2010PP2QN02

K.C.S.E Physics Q & A - MODEL 2010PP2QN01

K.C.S.E Physics Q & A - MODEL 2010PP1QN19

K.C.S.E Physics Q & A - MODEL 2010PP1QN18

Figure 8 shows a stone of mass 4.0kg immersed in water and suspended from a spring balance with a string. The beaker was placed on a compression balance whose reading was 85N. The density of the stone was 3000kgm-3 while the density of the liquid Was 800kgm-3. Determine the:

K.C.S.E Physics Q & A - MODEL 2010PP1QN17

Determine: (î) the heat absorbed by the water; (ii) heat absorbed by the electric kettle; (iii) the time taken for the water to boil; (iv) how much longer it will take to boil away all the water

K.C.S.E Physics Q & A - MODEL 2010PP1QN16

K.C.S.E Physics Q & A - MODEL 2010PP1QN15

K.C.S.E Physics Q & A - MODEL 2010PP1QN14

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The wavelength of a radio wave is 1km. Determine its frequency.
(Take the speed of light as 3.0 x 108 ms^-1)

Figure 8 shows a stone of mass 4.0kg immersed in water and suspended from a spring balance with a string. The beaker was placed on a compression balance whose reading was 85N. The density of the stone was 3000kgm^-3 while the density of the liquid Was 800kgm^-3.
Determine the:

Determine:
(î) the heat absorbed by the water;
(ii) heat absorbed by the electric kettle;
(iii) the time taken for the water to boil;
(iv) how much longer it will take to boil away all the water